diff --git a/config.c b/config.c
index 01d58abd..c4c932a9 100644
--- a/config.c
+++ b/config.c
@@ -16,7 +16,7 @@
 #define HOST_BOX_TITLE "Host Name (or IP address)"
 #define PORT_BOX_TITLE "Port"
 
-void conf_radiobutton_handler(union control *ctrl, dlgparam *dlg,
+void conf_radiobutton_handler(dlgcontrol *ctrl, dlgparam *dlg,
                               void *data, int event)
 {
     int button;
@@ -44,7 +44,7 @@ void conf_radiobutton_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-void conf_radiobutton_bool_handler(union control *ctrl, dlgparam *dlg,
+void conf_radiobutton_bool_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                    void *data, int event)
 {
     int button;
@@ -72,7 +72,7 @@ void conf_radiobutton_bool_handler(union control *ctrl, dlgparam *dlg,
 }
 
 #define CHECKBOX_INVERT (1<<30)
-void conf_checkbox_handler(union control *ctrl, dlgparam *dlg,
+void conf_checkbox_handler(dlgcontrol *ctrl, dlgparam *dlg,
                            void *data, int event)
 {
     int key;
@@ -104,7 +104,7 @@ void conf_checkbox_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-void conf_editbox_handler(union control *ctrl, dlgparam *dlg,
+void conf_editbox_handler(dlgcontrol *ctrl, dlgparam *dlg,
                           void *data, int event)
 {
     /*
@@ -153,7 +153,7 @@ void conf_editbox_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-void conf_filesel_handler(union control *ctrl, dlgparam *dlg,
+void conf_filesel_handler(dlgcontrol *ctrl, dlgparam *dlg,
                           void *data, int event)
 {
     int key = ctrl->fileselect.context.i;
@@ -169,7 +169,7 @@ void conf_filesel_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-void conf_fontsel_handler(union control *ctrl, dlgparam *dlg,
+void conf_fontsel_handler(dlgcontrol *ctrl, dlgparam *dlg,
                           void *data, int event)
 {
     int key = ctrl->fontselect.context.i;
@@ -185,7 +185,7 @@ void conf_fontsel_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void config_host_handler(union control *ctrl, dlgparam *dlg,
+static void config_host_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                 void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -217,7 +217,7 @@ static void config_host_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void config_port_handler(union control *ctrl, dlgparam *dlg,
+static void config_port_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                 void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -258,7 +258,7 @@ static void config_port_handler(union control *ctrl, dlgparam *dlg,
 }
 
 struct hostport {
-    union control *host, *port, *protradio, *protlist;
+    dlgcontrol *host, *port, *protradio, *protlist;
     bool mid_refresh;
 };
 
@@ -269,7 +269,7 @@ struct hostport {
  * and refreshes both host and port boxes when switching to/from the
  * serial backend.
  */
-static void config_protocols_handler(union control *ctrl, dlgparam *dlg,
+static void config_protocols_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                      void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -422,7 +422,7 @@ static void config_protocols_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void loggingbuttons_handler(union control *ctrl, dlgparam *dlg,
+static void loggingbuttons_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                    void *data, int event)
 {
     int button;
@@ -451,7 +451,7 @@ static void loggingbuttons_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void numeric_keypad_handler(union control *ctrl, dlgparam *dlg,
+static void numeric_keypad_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                    void *data, int event)
 {
     int button;
@@ -482,7 +482,7 @@ static void numeric_keypad_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void cipherlist_handler(union control *ctrl, dlgparam *dlg,
+static void cipherlist_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -528,7 +528,7 @@ static void cipherlist_handler(union control *ctrl, dlgparam *dlg,
 }
 
 #ifndef NO_GSSAPI
-static void gsslist_handler(union control *ctrl, dlgparam *dlg,
+static void gsslist_handler(dlgcontrol *ctrl, dlgparam *dlg,
                             void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -555,7 +555,7 @@ static void gsslist_handler(union control *ctrl, dlgparam *dlg,
 }
 #endif
 
-static void kexlist_handler(union control *ctrl, dlgparam *dlg,
+static void kexlist_handler(dlgcontrol *ctrl, dlgparam *dlg,
                             void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -601,7 +601,7 @@ static void kexlist_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void hklist_handler(union control *ctrl, dlgparam *dlg,
+static void hklist_handler(dlgcontrol *ctrl, dlgparam *dlg,
                             void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -645,7 +645,7 @@ static void hklist_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void printerbox_handler(union control *ctrl, dlgparam *dlg,
+static void printerbox_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -681,7 +681,7 @@ static void printerbox_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void codepage_handler(union control *ctrl, dlgparam *dlg,
+static void codepage_handler(dlgcontrol *ctrl, dlgparam *dlg,
                              void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -705,7 +705,7 @@ static void codepage_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void sshbug_handler(union control *ctrl, dlgparam *dlg,
+static void sshbug_handler(dlgcontrol *ctrl, dlgparam *dlg,
                            void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -738,7 +738,7 @@ static void sshbug_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void sshbug_handler_manual_only(union control *ctrl, dlgparam *dlg,
+static void sshbug_handler_manual_only(dlgcontrol *ctrl, dlgparam *dlg,
                                        void *data, int event)
 {
     /*
@@ -770,8 +770,8 @@ static void sshbug_handler_manual_only(union control *ctrl, dlgparam *dlg,
 }
 
 struct sessionsaver_data {
-    union control *editbox, *listbox, *loadbutton, *savebutton, *delbutton;
-    union control *okbutton, *cancelbutton;
+    dlgcontrol *editbox, *listbox, *loadbutton, *savebutton, *delbutton;
+    dlgcontrol *okbutton, *cancelbutton;
     struct sesslist sesslist;
     bool midsession;
     char *savedsession;     /* the current contents of ssd->editbox */
@@ -813,7 +813,7 @@ static bool load_selected_session(
     return true;
 }
 
-static void sessionsaver_handler(union control *ctrl, dlgparam *dlg,
+static void sessionsaver_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                  void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -951,10 +951,10 @@ static void sessionsaver_handler(union control *ctrl, dlgparam *dlg,
 }
 
 struct charclass_data {
-    union control *listbox, *editbox, *button;
+    dlgcontrol *listbox, *editbox, *button;
 };
 
-static void charclass_handler(union control *ctrl, dlgparam *dlg,
+static void charclass_handler(dlgcontrol *ctrl, dlgparam *dlg,
                               void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -992,7 +992,7 @@ static void charclass_handler(union control *ctrl, dlgparam *dlg,
 }
 
 struct colour_data {
-    union control *listbox, *redit, *gedit, *bedit, *button;
+    dlgcontrol *listbox, *redit, *gedit, *bedit, *button;
 };
 
 /* Array of the user-visible colour names defined in the list macro in
@@ -1003,7 +1003,7 @@ static const char *const colours[] = {
     #undef CONF_COLOUR_NAME_DECL
 };
 
-static void colour_handler(union control *ctrl, dlgparam *dlg,
+static void colour_handler(dlgcontrol *ctrl, dlgparam *dlg,
                             void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -1109,10 +1109,10 @@ static void colour_handler(union control *ctrl, dlgparam *dlg,
 }
 
 struct ttymodes_data {
-    union control *valradio, *valbox, *setbutton, *listbox;
+    dlgcontrol *valradio, *valbox, *setbutton, *listbox;
 };
 
-static void ttymodes_handler(union control *ctrl, dlgparam *dlg,
+static void ttymodes_handler(dlgcontrol *ctrl, dlgparam *dlg,
                              void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -1194,10 +1194,10 @@ static void ttymodes_handler(union control *ctrl, dlgparam *dlg,
 }
 
 struct environ_data {
-    union control *varbox, *valbox, *addbutton, *rembutton, *listbox;
+    dlgcontrol *varbox, *valbox, *addbutton, *rembutton, *listbox;
 };
 
-static void environ_handler(union control *ctrl, dlgparam *dlg,
+static void environ_handler(dlgcontrol *ctrl, dlgparam *dlg,
                             void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -1266,14 +1266,14 @@ static void environ_handler(union control *ctrl, dlgparam *dlg,
 }
 
 struct portfwd_data {
-    union control *addbutton, *rembutton, *listbox;
-    union control *sourcebox, *destbox, *direction;
+    dlgcontrol *addbutton, *rembutton, *listbox;
+    dlgcontrol *sourcebox, *destbox, *direction;
 #ifndef NO_IPV6
-    union control *addressfamily;
+    dlgcontrol *addressfamily;
 #endif
 };
 
-static void portfwd_handler(union control *ctrl, dlgparam *dlg,
+static void portfwd_handler(dlgcontrol *ctrl, dlgparam *dlg,
                             void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -1434,10 +1434,10 @@ static void portfwd_handler(union control *ctrl, dlgparam *dlg,
 }
 
 struct manual_hostkey_data {
-    union control *addbutton, *rembutton, *listbox, *keybox;
+    dlgcontrol *addbutton, *rembutton, *listbox, *keybox;
 };
 
-static void manual_hostkey_handler(union control *ctrl, dlgparam *dlg,
+static void manual_hostkey_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                    void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -1500,7 +1500,7 @@ static void manual_hostkey_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void clipboard_selector_handler(union control *ctrl, dlgparam *dlg,
+static void clipboard_selector_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                        void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -1601,7 +1601,7 @@ static void clipboard_control(struct controlset *s, const char *label,
 #endif
 }
 
-static void serial_parity_handler(union control *ctrl, dlgparam *dlg,
+static void serial_parity_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                   void *data, int event)
 {
     static const struct {
@@ -1656,7 +1656,7 @@ static void serial_parity_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void serial_flow_handler(union control *ctrl, dlgparam *dlg,
+static void serial_flow_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                 void *data, int event)
 {
     static const struct {
@@ -1709,7 +1709,7 @@ static void serial_flow_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-void proxy_type_handler(union control *ctrl, dlgparam *dlg,
+void proxy_type_handler(dlgcontrol *ctrl, dlgparam *dlg,
                         void *data, int event)
 {
     Conf *conf = (Conf *)data;
@@ -1763,7 +1763,7 @@ void proxy_type_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void host_ca_button_handler(union control *ctrl, dlgparam *dp,
+static void host_ca_button_handler(dlgcontrol *ctrl, dlgparam *dp,
                                    void *data, int event)
 {
     if (event == EVENT_ACTION)
@@ -1782,7 +1782,7 @@ void setup_config_box(struct controlbox *b, bool midsession,
     struct environ_data *ed;
     struct portfwd_data *pfd;
     struct manual_hostkey_data *mh;
-    union control *c;
+    dlgcontrol *c;
     bool resize_forbidden = false;
     char *str;
 
@@ -3318,11 +3318,11 @@ void setup_config_box(struct controlbox *b, bool midsession,
 }
 
 struct ca_state {
-    union control *ca_name_edit;
-    union control *ca_reclist;
-    union control *ca_pubkey_edit;
-    union control *ca_wclist;
-    union control *ca_wc_edit;
+    dlgcontrol *ca_name_edit;
+    dlgcontrol *ca_reclist;
+    dlgcontrol *ca_pubkey_edit;
+    dlgcontrol *ca_wclist;
+    dlgcontrol *ca_wc_edit;
     char *name, *pubkey, *wc;
     tree234 *ca_names;                 /* stores plain 'char *' */
     tree234 *host_wcs;                 /* stores plain 'char *' */
@@ -3416,14 +3416,14 @@ static void ca_load_selected_record(struct ca_state *st, dlgparam *dp)
     dlg_refresh(st->ca_wclist, dp);
 }
 
-static void ca_ok_handler(union control *ctrl, dlgparam *dp,
+static void ca_ok_handler(dlgcontrol *ctrl, dlgparam *dp,
                           void *data, int event)
 {
     if (event == EVENT_ACTION)
         dlg_end(dp, 0);
 }
 
-static void ca_name_handler(union control *ctrl, dlgparam *dp,
+static void ca_name_handler(dlgcontrol *ctrl, dlgparam *dp,
                             void *data, int event)
 {
     struct ca_state *st = (struct ca_state *)ctrl->generic.context.p;
@@ -3444,7 +3444,7 @@ static void ca_name_handler(union control *ctrl, dlgparam *dp,
     }
 }
 
-static void ca_reclist_handler(union control *ctrl, dlgparam *dp,
+static void ca_reclist_handler(dlgcontrol *ctrl, dlgparam *dp,
                                void *data, int event)
 {
     struct ca_state *st = (struct ca_state *)ctrl->generic.context.p;
@@ -3461,7 +3461,7 @@ static void ca_reclist_handler(union control *ctrl, dlgparam *dp,
     }
 }
 
-static void ca_load_handler(union control *ctrl, dlgparam *dp,
+static void ca_load_handler(dlgcontrol *ctrl, dlgparam *dp,
                             void *data, int event)
 {
     struct ca_state *st = (struct ca_state *)ctrl->generic.context.p;
@@ -3470,7 +3470,7 @@ static void ca_load_handler(union control *ctrl, dlgparam *dp,
     }
 }
 
-static void ca_save_handler(union control *ctrl, dlgparam *dp,
+static void ca_save_handler(dlgcontrol *ctrl, dlgparam *dp,
                             void *data, int event)
 {
     struct ca_state *st = (struct ca_state *)ctrl->generic.context.p;
@@ -3496,7 +3496,7 @@ static void ca_save_handler(union control *ctrl, dlgparam *dp,
     }
 }
 
-static void ca_delete_handler(union control *ctrl, dlgparam *dp,
+static void ca_delete_handler(dlgcontrol *ctrl, dlgparam *dp,
                               void *data, int event)
 {
     struct ca_state *st = (struct ca_state *)ctrl->generic.context.p;
@@ -3523,7 +3523,7 @@ static void ca_delete_handler(union control *ctrl, dlgparam *dp,
     }
 }
 
-static void ca_pubkey_handler(union control *ctrl, dlgparam *dp,
+static void ca_pubkey_handler(dlgcontrol *ctrl, dlgparam *dp,
                             void *data, int event)
 {
     struct ca_state *st = (struct ca_state *)ctrl->generic.context.p;
@@ -3535,7 +3535,7 @@ static void ca_pubkey_handler(union control *ctrl, dlgparam *dp,
     }
 }
 
-static void ca_wclist_handler(union control *ctrl, dlgparam *dp,
+static void ca_wclist_handler(dlgcontrol *ctrl, dlgparam *dp,
                               void *data, int event)
 {
     struct ca_state *st = (struct ca_state *)ctrl->generic.context.p;
@@ -3549,7 +3549,7 @@ static void ca_wclist_handler(union control *ctrl, dlgparam *dp,
     }
 }
 
-static void ca_wc_edit_handler(union control *ctrl, dlgparam *dp,
+static void ca_wc_edit_handler(dlgcontrol *ctrl, dlgparam *dp,
                                void *data, int event)
 {
     struct ca_state *st = (struct ca_state *)ctrl->generic.context.p;
@@ -3561,7 +3561,7 @@ static void ca_wc_edit_handler(union control *ctrl, dlgparam *dp,
     }
 }
 
-static void ca_wc_add_handler(union control *ctrl, dlgparam *dp,
+static void ca_wc_add_handler(dlgcontrol *ctrl, dlgparam *dp,
                               void *data, int event)
 {
     struct ca_state *st = (struct ca_state *)ctrl->generic.context.p;
@@ -3582,7 +3582,7 @@ static void ca_wc_add_handler(union control *ctrl, dlgparam *dp,
     }
 }
 
-static void ca_wc_rem_handler(union control *ctrl, dlgparam *dp,
+static void ca_wc_rem_handler(dlgcontrol *ctrl, dlgparam *dp,
                               void *data, int event)
 {
     struct ca_state *st = (struct ca_state *)ctrl->generic.context.p;
@@ -3608,7 +3608,7 @@ static void ca_wc_rem_handler(union control *ctrl, dlgparam *dp,
 void setup_ca_config_box(struct controlbox *b)
 {
     struct controlset *s;
-    union control *c;
+    dlgcontrol *c;
 
     /* Internal state for manipulating the host CA system */
     struct ca_state *st = (struct ca_state *)ctrl_alloc_with_free(
diff --git a/defs.h b/defs.h
index d9f2e355..063c05cd 100644
--- a/defs.h
+++ b/defs.h
@@ -172,6 +172,7 @@ typedef struct NTRUKeyPair NTRUKeyPair;
 typedef struct NTRUEncodeSchedule NTRUEncodeSchedule;
 
 typedef struct dlgparam dlgparam;
+typedef union control dlgcontrol;
 
 typedef struct settings_w settings_w;
 typedef struct settings_r settings_r;
diff --git a/dialog.c b/dialog.c
index 7409daaa..79ef7a10 100644
--- a/dialog.c
+++ b/dialog.c
@@ -204,11 +204,11 @@ void *ctrl_alloc(struct controlbox *b, size_t size)
     return ctrl_alloc_with_free(b, size, ctrl_default_free);
 }
 
-static union control *ctrl_new(struct controlset *s, int type,
-                               intorptr helpctx, handler_fn handler,
-                               intorptr context)
+static dlgcontrol *ctrl_new(struct controlset *s, int type,
+                            intorptr helpctx, handler_fn handler,
+                            intorptr context)
 {
-    union control *c = snew(union control);
+    dlgcontrol *c = snew(dlgcontrol);
     sgrowarray(s->ctrls, s->ctrlsize, s->ncontrols);
     s->ctrls[s->ncontrols++] = c;
     /*
@@ -226,9 +226,9 @@ static union control *ctrl_new(struct controlset *s, int type,
 }
 
 /* `ncolumns' is followed by that many percentages, as integers. */
-union control *ctrl_columns(struct controlset *s, int ncolumns, ...)
+dlgcontrol *ctrl_columns(struct controlset *s, int ncolumns, ...)
 {
-    union control *c = ctrl_new(s, CTRL_COLUMNS, P(NULL), NULL, P(NULL));
+    dlgcontrol *c = ctrl_new(s, CTRL_COLUMNS, P(NULL), NULL, P(NULL));
     assert(s->ncolumns == 1 || ncolumns == 1);
     c->columns.ncols = ncolumns;
     s->ncolumns = ncolumns;
@@ -246,12 +246,12 @@ union control *ctrl_columns(struct controlset *s, int ncolumns, ...)
     return c;
 }
 
-union control *ctrl_editbox(struct controlset *s, const char *label,
-                            char shortcut, int percentage,
-                            intorptr helpctx, handler_fn handler,
-                            intorptr context, intorptr context2)
+dlgcontrol *ctrl_editbox(struct controlset *s, const char *label,
+                         char shortcut, int percentage,
+                         intorptr helpctx, handler_fn handler,
+                         intorptr context, intorptr context2)
 {
-    union control *c = ctrl_new(s, CTRL_EDITBOX, helpctx, handler, context);
+    dlgcontrol *c = ctrl_new(s, CTRL_EDITBOX, helpctx, handler, context);
     c->editbox.label = label ? dupstr(label) : NULL;
     c->editbox.shortcut = shortcut;
     c->editbox.percentwidth = percentage;
@@ -261,12 +261,12 @@ union control *ctrl_editbox(struct controlset *s, const char *label,
     return c;
 }
 
-union control *ctrl_combobox(struct controlset *s, const char *label,
-                             char shortcut, int percentage,
-                             intorptr helpctx, handler_fn handler,
-                             intorptr context, intorptr context2)
+dlgcontrol *ctrl_combobox(struct controlset *s, const char *label,
+                          char shortcut, int percentage,
+                          intorptr helpctx, handler_fn handler,
+                          intorptr context, intorptr context2)
 {
-    union control *c = ctrl_new(s, CTRL_EDITBOX, helpctx, handler, context);
+    dlgcontrol *c = ctrl_new(s, CTRL_EDITBOX, helpctx, handler, context);
     c->editbox.label = label ? dupstr(label) : NULL;
     c->editbox.shortcut = shortcut;
     c->editbox.percentwidth = percentage;
@@ -282,13 +282,13 @@ union control *ctrl_combobox(struct controlset *s, const char *label,
  * title is expected to be followed by a shortcut _iff_ `shortcut'
  * is NO_SHORTCUT.
  */
-union control *ctrl_radiobuttons(struct controlset *s, const char *label,
-                                 char shortcut, int ncolumns, intorptr helpctx,
-                                 handler_fn handler, intorptr context, ...)
+dlgcontrol *ctrl_radiobuttons(struct controlset *s, const char *label,
+                              char shortcut, int ncolumns, intorptr helpctx,
+                              handler_fn handler, intorptr context, ...)
 {
     va_list ap;
     int i;
-    union control *c = ctrl_new(s, CTRL_RADIO, helpctx, handler, context);
+    dlgcontrol *c = ctrl_new(s, CTRL_RADIO, helpctx, handler, context);
     c->radio.label = label ? dupstr(label) : NULL;
     c->radio.shortcut = shortcut;
     c->radio.ncolumns = ncolumns;
@@ -328,11 +328,11 @@ union control *ctrl_radiobuttons(struct controlset *s, const char *label,
     return c;
 }
 
-union control *ctrl_pushbutton(struct controlset *s, const char *label,
-                               char shortcut, intorptr helpctx,
-                               handler_fn handler, intorptr context)
+dlgcontrol *ctrl_pushbutton(struct controlset *s, const char *label,
+                            char shortcut, intorptr helpctx,
+                            handler_fn handler, intorptr context)
 {
-    union control *c = ctrl_new(s, CTRL_BUTTON, helpctx, handler, context);
+    dlgcontrol *c = ctrl_new(s, CTRL_BUTTON, helpctx, handler, context);
     c->button.label = label ? dupstr(label) : NULL;
     c->button.shortcut = shortcut;
     c->button.isdefault = false;
@@ -340,11 +340,11 @@ union control *ctrl_pushbutton(struct controlset *s, const char *label,
     return c;
 }
 
-union control *ctrl_listbox(struct controlset *s, const char *label,
-                            char shortcut, intorptr helpctx,
-                            handler_fn handler, intorptr context)
+dlgcontrol *ctrl_listbox(struct controlset *s, const char *label,
+                         char shortcut, intorptr helpctx,
+                         handler_fn handler, intorptr context)
 {
-    union control *c = ctrl_new(s, CTRL_LISTBOX, helpctx, handler, context);
+    dlgcontrol *c = ctrl_new(s, CTRL_LISTBOX, helpctx, handler, context);
     c->listbox.label = label ? dupstr(label) : NULL;
     c->listbox.shortcut = shortcut;
     c->listbox.height = 5;             /* *shrug* a plausible default */
@@ -357,11 +357,11 @@ union control *ctrl_listbox(struct controlset *s, const char *label,
     return c;
 }
 
-union control *ctrl_droplist(struct controlset *s, const char *label,
-                             char shortcut, int percentage, intorptr helpctx,
-                             handler_fn handler, intorptr context)
+dlgcontrol *ctrl_droplist(struct controlset *s, const char *label,
+                          char shortcut, int percentage, intorptr helpctx,
+                          handler_fn handler, intorptr context)
 {
-    union control *c = ctrl_new(s, CTRL_LISTBOX, helpctx, handler, context);
+    dlgcontrol *c = ctrl_new(s, CTRL_LISTBOX, helpctx, handler, context);
     c->listbox.label = label ? dupstr(label) : NULL;
     c->listbox.shortcut = shortcut;
     c->listbox.height = 0;             /* means it's a drop-down list */
@@ -374,11 +374,11 @@ union control *ctrl_droplist(struct controlset *s, const char *label,
     return c;
 }
 
-union control *ctrl_draglist(struct controlset *s, const char *label,
-                             char shortcut, intorptr helpctx,
-                             handler_fn handler, intorptr context)
+dlgcontrol *ctrl_draglist(struct controlset *s, const char *label,
+                          char shortcut, intorptr helpctx,
+                          handler_fn handler, intorptr context)
 {
-    union control *c = ctrl_new(s, CTRL_LISTBOX, helpctx, handler, context);
+    dlgcontrol *c = ctrl_new(s, CTRL_LISTBOX, helpctx, handler, context);
     c->listbox.label = label ? dupstr(label) : NULL;
     c->listbox.shortcut = shortcut;
     c->listbox.height = 5;             /* *shrug* a plausible default */
@@ -391,12 +391,12 @@ union control *ctrl_draglist(struct controlset *s, const char *label,
     return c;
 }
 
-union control *ctrl_filesel(struct controlset *s, const char *label,
-                            char shortcut, const char *filter, bool write,
-                            const char *title, intorptr helpctx,
-                            handler_fn handler, intorptr context)
+dlgcontrol *ctrl_filesel(struct controlset *s, const char *label,
+                         char shortcut, const char *filter, bool write,
+                         const char *title, intorptr helpctx,
+                         handler_fn handler, intorptr context)
 {
-    union control *c = ctrl_new(s, CTRL_FILESELECT, helpctx, handler, context);
+    dlgcontrol *c = ctrl_new(s, CTRL_FILESELECT, helpctx, handler, context);
     c->fileselect.label = label ? dupstr(label) : NULL;
     c->fileselect.shortcut = shortcut;
     c->fileselect.filter = filter;
@@ -405,42 +405,42 @@ union control *ctrl_filesel(struct controlset *s, const char *label,
     return c;
 }
 
-union control *ctrl_fontsel(struct controlset *s, const char *label,
-                            char shortcut, intorptr helpctx,
-                            handler_fn handler, intorptr context)
+dlgcontrol *ctrl_fontsel(struct controlset *s, const char *label,
+                         char shortcut, intorptr helpctx,
+                         handler_fn handler, intorptr context)
 {
-    union control *c = ctrl_new(s, CTRL_FONTSELECT, helpctx, handler, context);
+    dlgcontrol *c = ctrl_new(s, CTRL_FONTSELECT, helpctx, handler, context);
     c->fontselect.label = label ? dupstr(label) : NULL;
     c->fontselect.shortcut = shortcut;
     return c;
 }
 
-union control *ctrl_tabdelay(struct controlset *s, union control *ctrl)
+dlgcontrol *ctrl_tabdelay(struct controlset *s, dlgcontrol *ctrl)
 {
-    union control *c = ctrl_new(s, CTRL_TABDELAY, P(NULL), NULL, P(NULL));
+    dlgcontrol *c = ctrl_new(s, CTRL_TABDELAY, P(NULL), NULL, P(NULL));
     c->tabdelay.ctrl = ctrl;
     return c;
 }
 
-union control *ctrl_text(struct controlset *s, const char *text,
-                         intorptr helpctx)
+dlgcontrol *ctrl_text(struct controlset *s, const char *text,
+                      intorptr helpctx)
 {
-    union control *c = ctrl_new(s, CTRL_TEXT, helpctx, NULL, P(NULL));
+    dlgcontrol *c = ctrl_new(s, CTRL_TEXT, helpctx, NULL, P(NULL));
     c->text.label = dupstr(text);
     return c;
 }
 
-union control *ctrl_checkbox(struct controlset *s, const char *label,
-                             char shortcut, intorptr helpctx,
-                             handler_fn handler, intorptr context)
+dlgcontrol *ctrl_checkbox(struct controlset *s, const char *label,
+                          char shortcut, intorptr helpctx,
+                          handler_fn handler, intorptr context)
 {
-    union control *c = ctrl_new(s, CTRL_CHECKBOX, helpctx, handler, context);
+    dlgcontrol *c = ctrl_new(s, CTRL_CHECKBOX, helpctx, handler, context);
     c->checkbox.label = label ? dupstr(label) : NULL;
     c->checkbox.shortcut = shortcut;
     return c;
 }
 
-void ctrl_free(union control *ctrl)
+void ctrl_free(dlgcontrol *ctrl)
 {
     int i;
 
diff --git a/dialog.h b/dialog.h
index 86ebfc20..28d0916c 100644
--- a/dialog.h
+++ b/dialog.h
@@ -73,8 +73,6 @@ PREFIX intorptr P(void *p) { intorptr ret; ret.p = p; return ret; }
 #define COLUMN_START(field) ( (field) & 0xFFFF )
 #define COLUMN_SPAN(field) ( (((field) >> 16) & 0xFFFF) + 1 )
 
-union control;
-
 /*
  * The number of event types is being deliberately kept small, on
  * the grounds that not all platforms might be able to report a
@@ -103,7 +101,7 @@ enum {
     EVENT_SELCHANGE,
     EVENT_CALLBACK
 };
-typedef void (*handler_fn)(union control *ctrl, dlgparam *dp,
+typedef void (*handler_fn)(dlgcontrol *ctrl, dlgparam *dp,
                            void *data, int event);
 
 #define STANDARD_PREFIX \
@@ -114,7 +112,7 @@ typedef void (*handler_fn)(union control *ctrl, dlgparam *dp,
         handler_fn handler; \
         intorptr context; \
         intorptr helpctx; \
-        union control *align_next_to
+        dlgcontrol *align_next_to
 
 union control {
     /*
@@ -191,11 +189,11 @@ union control {
          * instantiated, the first one is already there to be referred
          * to.
          */
-        union control *align_next_to;
+        dlgcontrol *align_next_to;
     } generic;
     struct {
         STANDARD_PREFIX;
-        union control *ctrl;
+        dlgcontrol *ctrl;
     } tabdelay;
     struct {
         STANDARD_PREFIX;
@@ -422,7 +420,7 @@ union control {
 #undef STANDARD_PREFIX
 
 /*
- * `controlset' is a container holding an array of `union control'
+ * `controlset' is a container holding an array of `dlgcontrol'
  * structures, together with a panel name and a title for the whole
  * set. In Windows and any similar-looking GUI, each `controlset'
  * in the config will be a container box within a panel.
@@ -435,9 +433,9 @@ struct controlset {
     char *boxname;                     /* internal short name of controlset */
     char *boxtitle;                    /* title of container box */
     int ncolumns;                      /* current no. of columns at bottom */
-    size_t ncontrols;                  /* number of `union control' in array */
+    size_t ncontrols;                  /* number of `dlgcontrol' in array */
     size_t ctrlsize;                   /* allocated size of array */
-    union control **ctrls;             /* actual array */
+    dlgcontrol **ctrls;                /* actual array */
 };
 
 typedef void (*ctrl_freefn_t)(void *);    /* used by ctrl_alloc_with_free */
@@ -471,7 +469,7 @@ struct controlset *ctrl_getset(struct controlbox *, const char *path,
                                const char *name, const char *boxtitle);
 void ctrl_free_set(struct controlset *);
 
-void ctrl_free(union control *);
+void ctrl_free(dlgcontrol *);
 
 /*
  * This function works like `malloc', but the memory it returns
@@ -490,73 +488,73 @@ void *ctrl_alloc_with_free(struct controlbox *b, size_t size,
                            ctrl_freefn_t freefunc);
 
 /*
- * Individual routines to create `union control' structures in a controlset.
+ * Individual routines to create `dlgcontrol' structures in a controlset.
  *
  * Most of these routines allow the most common fields to be set
  * directly, and put default values in the rest. Each one returns a
- * pointer to the `union control' it created, so that final tweaks
+ * pointer to the `dlgcontrol' it created, so that final tweaks
  * can be made.
  */
 
 /* `ncolumns' is followed by that many percentages, as integers. */
-union control *ctrl_columns(struct controlset *, int ncolumns, ...);
-union control *ctrl_editbox(struct controlset *, const char *label,
-                            char shortcut, int percentage, intorptr helpctx,
-                            handler_fn handler,
-                            intorptr context, intorptr context2);
-union control *ctrl_combobox(struct controlset *, const char *label,
-                             char shortcut, int percentage, intorptr helpctx,
-                             handler_fn handler,
-                             intorptr context, intorptr context2);
+dlgcontrol *ctrl_columns(struct controlset *, int ncolumns, ...);
+dlgcontrol *ctrl_editbox(struct controlset *, const char *label,
+                         char shortcut, int percentage, intorptr helpctx,
+                         handler_fn handler,
+                         intorptr context, intorptr context2);
+dlgcontrol *ctrl_combobox(struct controlset *, const char *label,
+                          char shortcut, int percentage, intorptr helpctx,
+                          handler_fn handler,
+                          intorptr context, intorptr context2);
 /*
  * `ncolumns' is followed by (alternately) radio button titles and
  * intorptrs, until a NULL in place of a title string is seen. Each
  * title is expected to be followed by a shortcut _iff_ `shortcut'
  * is NO_SHORTCUT.
  */
-union control *ctrl_radiobuttons(struct controlset *, const char *label,
-                                 char shortcut, int ncolumns, intorptr helpctx,
-                                 handler_fn handler, intorptr context, ...);
-union control *ctrl_pushbutton(struct controlset *, const char *label,
-                               char shortcut, intorptr helpctx,
-                               handler_fn handler, intorptr context);
-union control *ctrl_listbox(struct controlset *, const char *label,
+dlgcontrol *ctrl_radiobuttons(struct controlset *, const char *label,
+                              char shortcut, int ncolumns, intorptr helpctx,
+                              handler_fn handler, intorptr context, ...);
+dlgcontrol *ctrl_pushbutton(struct controlset *, const char *label,
                             char shortcut, intorptr helpctx,
                             handler_fn handler, intorptr context);
-union control *ctrl_droplist(struct controlset *, const char *label,
-                             char shortcut, int percentage, intorptr helpctx,
-                             handler_fn handler, intorptr context);
-union control *ctrl_draglist(struct controlset *, const char *label,
-                             char shortcut, intorptr helpctx,
-                             handler_fn handler, intorptr context);
-union control *ctrl_filesel(struct controlset *, const char *label,
-                            char shortcut, const char *filter, bool write,
-                            const char *title, intorptr helpctx,
-                            handler_fn handler, intorptr context);
-union control *ctrl_fontsel(struct controlset *, const char *label,
-                            char shortcut, intorptr helpctx,
-                            handler_fn handler, intorptr context);
-union control *ctrl_text(struct controlset *, const char *text,
-                         intorptr helpctx);
-union control *ctrl_checkbox(struct controlset *, const char *label,
-                             char shortcut, intorptr helpctx,
-                             handler_fn handler, intorptr context);
-union control *ctrl_tabdelay(struct controlset *, union control *);
+dlgcontrol *ctrl_listbox(struct controlset *, const char *label,
+                         char shortcut, intorptr helpctx,
+                         handler_fn handler, intorptr context);
+dlgcontrol *ctrl_droplist(struct controlset *, const char *label,
+                          char shortcut, int percentage, intorptr helpctx,
+                          handler_fn handler, intorptr context);
+dlgcontrol *ctrl_draglist(struct controlset *, const char *label,
+                          char shortcut, intorptr helpctx,
+                          handler_fn handler, intorptr context);
+dlgcontrol *ctrl_filesel(struct controlset *, const char *label,
+                         char shortcut, const char *filter, bool write,
+                         const char *title, intorptr helpctx,
+                         handler_fn handler, intorptr context);
+dlgcontrol *ctrl_fontsel(struct controlset *, const char *label,
+                         char shortcut, intorptr helpctx,
+                         handler_fn handler, intorptr context);
+dlgcontrol *ctrl_text(struct controlset *, const char *text,
+                      intorptr helpctx);
+dlgcontrol *ctrl_checkbox(struct controlset *, const char *label,
+                          char shortcut, intorptr helpctx,
+                          handler_fn handler, intorptr context);
+dlgcontrol *ctrl_tabdelay(struct controlset *, dlgcontrol *);
 
 /*
  * Routines the platform-independent dialog code can call to read
  * and write the values of controls.
  */
-void dlg_radiobutton_set(union control *ctrl, dlgparam *dp, int whichbutton);
-int dlg_radiobutton_get(union control *ctrl, dlgparam *dp);
-void dlg_checkbox_set(union control *ctrl, dlgparam *dp, bool checked);
-bool dlg_checkbox_get(union control *ctrl, dlgparam *dp);
-void dlg_editbox_set(union control *ctrl, dlgparam *dp, char const *text);
-char *dlg_editbox_get(union control *ctrl, dlgparam *dp);   /* result must be freed by caller */
+void dlg_radiobutton_set(dlgcontrol *ctrl, dlgparam *dp, int whichbutton);
+int dlg_radiobutton_get(dlgcontrol *ctrl, dlgparam *dp);
+void dlg_checkbox_set(dlgcontrol *ctrl, dlgparam *dp, bool checked);
+bool dlg_checkbox_get(dlgcontrol *ctrl, dlgparam *dp);
+void dlg_editbox_set(dlgcontrol *ctrl, dlgparam *dp, char const *text);
+char *dlg_editbox_get(dlgcontrol *ctrl, dlgparam *dp);   /* result must be freed by caller */
 /* The `listbox' functions can also apply to combo boxes. */
-void dlg_listbox_clear(union control *ctrl, dlgparam *dp);
-void dlg_listbox_del(union control *ctrl, dlgparam *dp, int index);
-void dlg_listbox_add(union control *ctrl, dlgparam *dp, char const *text);
+void dlg_listbox_clear(dlgcontrol *ctrl, dlgparam *dp);
+void dlg_listbox_del(dlgcontrol *ctrl, dlgparam *dp, int index);
+void dlg_listbox_add(dlgcontrol *ctrl, dlgparam *dp, char const *text);
 /*
  * Each listbox entry may have a numeric id associated with it.
  * Note that some front ends only permit a string to be stored at
@@ -564,44 +562,44 @@ void dlg_listbox_add(union control *ctrl, dlgparam *dp, char const *text);
  * strings in any listbox then you MUST not assign them different
  * IDs and expect to get meaningful results back.
  */
-void dlg_listbox_addwithid(union control *ctrl, dlgparam *dp,
+void dlg_listbox_addwithid(dlgcontrol *ctrl, dlgparam *dp,
                            char const *text, int id);
-int dlg_listbox_getid(union control *ctrl, dlgparam *dp, int index);
+int dlg_listbox_getid(dlgcontrol *ctrl, dlgparam *dp, int index);
 /* dlg_listbox_index returns <0 if no single element is selected. */
-int dlg_listbox_index(union control *ctrl, dlgparam *dp);
-bool dlg_listbox_issel(union control *ctrl, dlgparam *dp, int index);
-void dlg_listbox_select(union control *ctrl, dlgparam *dp, int index);
-void dlg_text_set(union control *ctrl, dlgparam *dp, char const *text);
-void dlg_filesel_set(union control *ctrl, dlgparam *dp, Filename *fn);
-Filename *dlg_filesel_get(union control *ctrl, dlgparam *dp);
-void dlg_fontsel_set(union control *ctrl, dlgparam *dp, FontSpec *fn);
-FontSpec *dlg_fontsel_get(union control *ctrl, dlgparam *dp);
+int dlg_listbox_index(dlgcontrol *ctrl, dlgparam *dp);
+bool dlg_listbox_issel(dlgcontrol *ctrl, dlgparam *dp, int index);
+void dlg_listbox_select(dlgcontrol *ctrl, dlgparam *dp, int index);
+void dlg_text_set(dlgcontrol *ctrl, dlgparam *dp, char const *text);
+void dlg_filesel_set(dlgcontrol *ctrl, dlgparam *dp, Filename *fn);
+Filename *dlg_filesel_get(dlgcontrol *ctrl, dlgparam *dp);
+void dlg_fontsel_set(dlgcontrol *ctrl, dlgparam *dp, FontSpec *fn);
+FontSpec *dlg_fontsel_get(dlgcontrol *ctrl, dlgparam *dp);
 /*
  * Bracketing a large set of updates in these two functions will
  * cause the front end (if possible) to delay updating the screen
  * until it's all complete, thus avoiding flicker.
  */
-void dlg_update_start(union control *ctrl, dlgparam *dp);
-void dlg_update_done(union control *ctrl, dlgparam *dp);
+void dlg_update_start(dlgcontrol *ctrl, dlgparam *dp);
+void dlg_update_done(dlgcontrol *ctrl, dlgparam *dp);
 /*
  * Set input focus into a particular control.
  */
-void dlg_set_focus(union control *ctrl, dlgparam *dp);
+void dlg_set_focus(dlgcontrol *ctrl, dlgparam *dp);
 /*
  * Change the label text on a control.
  */
-void dlg_label_change(union control *ctrl, dlgparam *dp, char const *text);
+void dlg_label_change(dlgcontrol *ctrl, dlgparam *dp, char const *text);
 /*
  * Return the `ctrl' structure for the most recent control that had
  * the input focus apart from the one mentioned. This is NOT
  * GUARANTEED to work on all platforms, so don't base any critical
  * functionality on it!
  */
-union control *dlg_last_focused(union control *ctrl, dlgparam *dp);
+dlgcontrol *dlg_last_focused(dlgcontrol *ctrl, dlgparam *dp);
 /*
  * Find out whether a particular control is currently visible.
  */
-bool dlg_is_visible(union control *ctrl, dlgparam *dp);
+bool dlg_is_visible(dlgcontrol *ctrl, dlgparam *dp);
 /*
  * During event processing, you might well want to give an error
  * indication to the user. dlg_beep() is a quick and easy generic
@@ -629,9 +627,9 @@ void dlg_end(dlgparam *dp, int value);
  * dlg_coloursel_start() accepts an RGB triple which is used to
  * initialise the colour selector to its starting value.
  */
-void dlg_coloursel_start(union control *ctrl, dlgparam *dp,
+void dlg_coloursel_start(dlgcontrol *ctrl, dlgparam *dp,
                          int r, int g, int b);
-bool dlg_coloursel_results(union control *ctrl, dlgparam *dp,
+bool dlg_coloursel_results(dlgcontrol *ctrl, dlgparam *dp,
                            int *r, int *g, int *b);
 
 /*
@@ -643,7 +641,7 @@ bool dlg_coloursel_results(union control *ctrl, dlgparam *dp,
  * If `ctrl' is NULL, _all_ controls in the dialog get refreshed
  * (for loading or saving entire sets of settings).
  */
-void dlg_refresh(union control *ctrl, dlgparam *dp);
+void dlg_refresh(dlgcontrol *ctrl, dlgparam *dp);
 
 /*
  * Standard helper functions for reading a controlbox structure.
diff --git a/putty.h b/putty.h
index 5ceedbe1..fd5eea44 100644
--- a/putty.h
+++ b/putty.h
@@ -2570,17 +2570,16 @@ void cmdline_error(const char *, ...) PRINTF_LIKE(1, 2);
  * Exports from config.c.
  */
 struct controlbox;
-union control;
-void conf_radiobutton_handler(union control *ctrl, dlgparam *dlg,
+void conf_radiobutton_handler(dlgcontrol *ctrl, dlgparam *dlg,
                               void *data, int event);
 #define CHECKBOX_INVERT (1<<30)
-void conf_checkbox_handler(union control *ctrl, dlgparam *dlg,
+void conf_checkbox_handler(dlgcontrol *ctrl, dlgparam *dlg,
                            void *data, int event);
-void conf_editbox_handler(union control *ctrl, dlgparam *dlg,
+void conf_editbox_handler(dlgcontrol *ctrl, dlgparam *dlg,
                           void *data, int event);
-void conf_filesel_handler(union control *ctrl, dlgparam *dlg,
+void conf_filesel_handler(dlgcontrol *ctrl, dlgparam *dlg,
                           void *data, int event);
-void conf_fontsel_handler(union control *ctrl, dlgparam *dlg,
+void conf_fontsel_handler(dlgcontrol *ctrl, dlgparam *dlg,
                           void *data, int event);
 
 void setup_config_box(struct controlbox *b, bool midsession,
@@ -2593,7 +2592,7 @@ void show_ca_config_box(dlgparam *dlg);
 
 /* Visible outside config.c so that platforms can use it to recognise
  * the proxy type control */
-void proxy_type_handler(union control *ctrl, dlgparam *dlg,
+void proxy_type_handler(dlgcontrol *ctrl, dlgparam *dlg,
                         void *data, int event);
 /* And then they'll set this flag in its generic.context.i */
 #define PROXY_UI_FLAG_LOCAL 1 /* has a local proxy */
diff --git a/test/fuzzterm.c b/test/fuzzterm.c
index faea2dd7..8d20bef9 100644
--- a/test/fuzzterm.c
+++ b/test/fuzzterm.c
@@ -134,44 +134,44 @@ void timer_change_notify(unsigned long next) { }
 
 /* needed by config.c */
 
-void dlg_radiobutton_set(union control *ctrl, dlgparam *dp, int whichbutton) { }
-int dlg_radiobutton_get(union control *ctrl, dlgparam *dp) { return 0; }
-void dlg_checkbox_set(union control *ctrl, dlgparam *dp, bool checked) { }
-bool dlg_checkbox_get(union control *ctrl, dlgparam *dp) { return false; }
-void dlg_editbox_set(union control *ctrl, dlgparam *dp, char const *text) { }
-char *dlg_editbox_get(union control *ctrl, dlgparam *dp)
+void dlg_radiobutton_set(dlgcontrol *ctrl, dlgparam *dp, int whichbutton) { }
+int dlg_radiobutton_get(dlgcontrol *ctrl, dlgparam *dp) { return 0; }
+void dlg_checkbox_set(dlgcontrol *ctrl, dlgparam *dp, bool checked) { }
+bool dlg_checkbox_get(dlgcontrol *ctrl, dlgparam *dp) { return false; }
+void dlg_editbox_set(dlgcontrol *ctrl, dlgparam *dp, char const *text) { }
+char *dlg_editbox_get(dlgcontrol *ctrl, dlgparam *dp)
 { return dupstr("moo"); }
-void dlg_listbox_clear(union control *ctrl, dlgparam *dp) { }
-void dlg_listbox_del(union control *ctrl, dlgparam *dp, int index) { }
-void dlg_listbox_add(union control *ctrl, dlgparam *dp, char const *text) { }
-void dlg_listbox_addwithid(union control *ctrl, dlgparam *dp,
+void dlg_listbox_clear(dlgcontrol *ctrl, dlgparam *dp) { }
+void dlg_listbox_del(dlgcontrol *ctrl, dlgparam *dp, int index) { }
+void dlg_listbox_add(dlgcontrol *ctrl, dlgparam *dp, char const *text) { }
+void dlg_listbox_addwithid(dlgcontrol *ctrl, dlgparam *dp,
                            char const *text, int id) { }
-int dlg_listbox_getid(union control *ctrl, dlgparam *dp, int index)
+int dlg_listbox_getid(dlgcontrol *ctrl, dlgparam *dp, int index)
 { return 0; }
-int dlg_listbox_index(union control *ctrl, dlgparam *dp) { return -1; }
-bool dlg_listbox_issel(union control *ctrl, dlgparam *dp, int index)
+int dlg_listbox_index(dlgcontrol *ctrl, dlgparam *dp) { return -1; }
+bool dlg_listbox_issel(dlgcontrol *ctrl, dlgparam *dp, int index)
 { return false; }
-void dlg_listbox_select(union control *ctrl, dlgparam *dp, int index) { }
-void dlg_text_set(union control *ctrl, dlgparam *dp, char const *text) { }
-void dlg_filesel_set(union control *ctrl, dlgparam *dp, Filename *fn) { }
-Filename *dlg_filesel_get(union control *ctrl, dlgparam *dp) { return NULL; }
-void dlg_fontsel_set(union control *ctrl, dlgparam *dp, FontSpec *fn) { }
-FontSpec *dlg_fontsel_get(union control *ctrl, dlgparam *dp) { return NULL; }
-void dlg_update_start(union control *ctrl, dlgparam *dp) { }
-void dlg_update_done(union control *ctrl, dlgparam *dp) { }
-void dlg_set_focus(union control *ctrl, dlgparam *dp) { }
-void dlg_label_change(union control *ctrl, dlgparam *dp, char const *text) { }
-union control *dlg_last_focused(union control *ctrl, dlgparam *dp)
+void dlg_listbox_select(dlgcontrol *ctrl, dlgparam *dp, int index) { }
+void dlg_text_set(dlgcontrol *ctrl, dlgparam *dp, char const *text) { }
+void dlg_filesel_set(dlgcontrol *ctrl, dlgparam *dp, Filename *fn) { }
+Filename *dlg_filesel_get(dlgcontrol *ctrl, dlgparam *dp) { return NULL; }
+void dlg_fontsel_set(dlgcontrol *ctrl, dlgparam *dp, FontSpec *fn) { }
+FontSpec *dlg_fontsel_get(dlgcontrol *ctrl, dlgparam *dp) { return NULL; }
+void dlg_update_start(dlgcontrol *ctrl, dlgparam *dp) { }
+void dlg_update_done(dlgcontrol *ctrl, dlgparam *dp) { }
+void dlg_set_focus(dlgcontrol *ctrl, dlgparam *dp) { }
+void dlg_label_change(dlgcontrol *ctrl, dlgparam *dp, char const *text) { }
+dlgcontrol *dlg_last_focused(dlgcontrol *ctrl, dlgparam *dp)
 { return NULL; }
 void dlg_beep(dlgparam *dp) { }
 void dlg_error_msg(dlgparam *dp, const char *msg) { }
 void dlg_end(dlgparam *dp, int value) { }
-void dlg_coloursel_start(union control *ctrl, dlgparam *dp,
+void dlg_coloursel_start(dlgcontrol *ctrl, dlgparam *dp,
                          int r, int g, int b) { }
-bool dlg_coloursel_results(union control *ctrl, dlgparam *dp,
+bool dlg_coloursel_results(dlgcontrol *ctrl, dlgparam *dp,
                            int *r, int *g, int *b) { return false; }
-void dlg_refresh(union control *ctrl, dlgparam *dp) { }
-bool dlg_is_visible(union control *ctrl, dlgparam *dp) { return false; }
+void dlg_refresh(dlgcontrol *ctrl, dlgparam *dp) { }
+bool dlg_is_visible(dlgcontrol *ctrl, dlgparam *dp) { return false; }
 
 const int ngsslibs = 0;
 const char *const gsslibnames[0] = { };
diff --git a/unix/config-gtk.c b/unix/config-gtk.c
index 52e6e181..5f3d7e0b 100644
--- a/unix/config-gtk.c
+++ b/unix/config-gtk.c
@@ -10,7 +10,7 @@
 #include "dialog.h"
 #include "storage.h"
 
-static void about_handler(union control *ctrl, dlgparam *dlg,
+static void about_handler(dlgcontrol *ctrl, dlgparam *dlg,
                           void *data, int event)
 {
     if (event == EVENT_ACTION) {
@@ -21,7 +21,7 @@ static void about_handler(union control *ctrl, dlgparam *dlg,
 void gtk_setup_config_box(struct controlbox *b, bool midsession, void *win)
 {
     struct controlset *s, *s2;
-    union control *c;
+    dlgcontrol *c;
     int i;
 
     if (!midsession) {
@@ -59,7 +59,7 @@ void gtk_setup_config_box(struct controlbox *b, bool midsession, void *win)
             if (i < s->ncontrols-2) {
                 c = s->ctrls[s->ncontrols-1];
                 memmove(s->ctrls+i+2, s->ctrls+i+1,
-                        (s->ncontrols-i-2)*sizeof(union control *));
+                        (s->ncontrols-i-2)*sizeof(dlgcontrol *));
                 s->ctrls[i+1] = c;
             }
             break;
diff --git a/unix/config-unix.c b/unix/config-unix.c
index d832a18b..43d43bbd 100644
--- a/unix/config-unix.c
+++ b/unix/config-unix.c
@@ -13,7 +13,7 @@
 void unix_setup_config_box(struct controlbox *b, bool midsession, int protocol)
 {
     struct controlset *s;
-    union control *c;
+    dlgcontrol *c;
 
     /*
      * The Conf structure contains two Unix-specific elements which
diff --git a/unix/dialog.c b/unix/dialog.c
index edd08314..08572297 100644
--- a/unix/dialog.c
+++ b/unix/dialog.c
@@ -51,7 +51,7 @@ struct Shortcuts {
 struct selparam;
 
 struct uctrl {
-    union control *ctrl;
+    dlgcontrol *ctrl;
     GtkWidget *toplevel;
     GtkWidget **buttons; int nbuttons; /* for radio buttons */
     GtkWidget *entry;         /* for editbox, filesel, fontsel */
@@ -88,7 +88,7 @@ struct dlgparam {
     int flags;
     struct Shortcuts *shortcuts;
     GtkWidget *window, *cancelbutton;
-    union control *currfocus, *lastfocus;
+    dlgcontrol *currfocus, *lastfocus;
 #if !GTK_CHECK_VERSION(2,0,0)
     GtkWidget *currtreeitem, **treeitems;
     int ntreeitems;
@@ -166,7 +166,7 @@ static int uctrl_cmp_byctrl(void *av, void *bv)
 
 static int uctrl_cmp_byctrl_find(void *av, void *bv)
 {
-    union control *a = (union control *)av;
+    dlgcontrol *a = (dlgcontrol *)av;
     struct uctrl *b = (struct uctrl *)bv;
     if (a < b->ctrl)
         return -1;
@@ -236,7 +236,7 @@ static void dlg_add_uctrl(struct dlgparam *dp, struct uctrl *uc)
     add234(dp->bywidget, uc);
 }
 
-static struct uctrl *dlg_find_byctrl(struct dlgparam *dp, union control *ctrl)
+static struct uctrl *dlg_find_byctrl(struct dlgparam *dp, dlgcontrol *ctrl)
 {
     if (!dp->byctrl)
         return NULL;
@@ -257,7 +257,7 @@ static struct uctrl *dlg_find_bywidget(struct dlgparam *dp, GtkWidget *w)
     return ret;
 }
 
-union control *dlg_last_focused(union control *ctrl, dlgparam *dp)
+dlgcontrol *dlg_last_focused(dlgcontrol *ctrl, dlgparam *dp)
 {
     if (dp->currfocus != ctrl)
         return dp->currfocus;
@@ -265,7 +265,7 @@ union control *dlg_last_focused(union control *ctrl, dlgparam *dp)
         return dp->lastfocus;
 }
 
-void dlg_radiobutton_set(union control *ctrl, dlgparam *dp, int which)
+void dlg_radiobutton_set(dlgcontrol *ctrl, dlgparam *dp, int which)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
     assert(uc->ctrl->generic.type == CTRL_RADIO);
@@ -273,7 +273,7 @@ void dlg_radiobutton_set(union control *ctrl, dlgparam *dp, int which)
     gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(uc->buttons[which]), true);
 }
 
-int dlg_radiobutton_get(union control *ctrl, dlgparam *dp)
+int dlg_radiobutton_get(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
     int i;
@@ -286,21 +286,21 @@ int dlg_radiobutton_get(union control *ctrl, dlgparam *dp)
     return 0;                          /* got to return something */
 }
 
-void dlg_checkbox_set(union control *ctrl, dlgparam *dp, bool checked)
+void dlg_checkbox_set(dlgcontrol *ctrl, dlgparam *dp, bool checked)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
     assert(uc->ctrl->generic.type == CTRL_CHECKBOX);
     gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(uc->toplevel), checked);
 }
 
-bool dlg_checkbox_get(union control *ctrl, dlgparam *dp)
+bool dlg_checkbox_get(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
     assert(uc->ctrl->generic.type == CTRL_CHECKBOX);
     return gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(uc->toplevel));
 }
 
-void dlg_editbox_set(union control *ctrl, dlgparam *dp, char const *text)
+void dlg_editbox_set(dlgcontrol *ctrl, dlgparam *dp, char const *text)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
     GtkWidget *entry;
@@ -338,7 +338,7 @@ void dlg_editbox_set(union control *ctrl, dlgparam *dp, char const *text)
     sfree(tmpstring);
 }
 
-char *dlg_editbox_get(union control *ctrl, dlgparam *dp)
+char *dlg_editbox_get(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
     assert(uc->ctrl->generic.type == CTRL_EDITBOX);
@@ -367,7 +367,7 @@ static void container_remove_and_destroy(GtkWidget *w, gpointer data)
 #endif
 
 /* The `listbox' functions can also apply to combo boxes. */
-void dlg_listbox_clear(union control *ctrl, dlgparam *dp)
+void dlg_listbox_clear(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
 
@@ -395,7 +395,7 @@ void dlg_listbox_clear(union control *ctrl, dlgparam *dp)
     unreachable("bad control type in listbox_clear");
 }
 
-void dlg_listbox_del(union control *ctrl, dlgparam *dp, int index)
+void dlg_listbox_del(dlgcontrol *ctrl, dlgparam *dp, int index)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
 
@@ -429,7 +429,7 @@ void dlg_listbox_del(union control *ctrl, dlgparam *dp, int index)
     unreachable("bad control type in listbox_del");
 }
 
-void dlg_listbox_add(union control *ctrl, dlgparam *dp, char const *text)
+void dlg_listbox_add(dlgcontrol *ctrl, dlgparam *dp, char const *text)
 {
     dlg_listbox_addwithid(ctrl, dp, text, 0);
 }
@@ -441,7 +441,7 @@ void dlg_listbox_add(union control *ctrl, dlgparam *dp, char const *text)
  * strings in any listbox then you MUST not assign them different
  * IDs and expect to get meaningful results back.
  */
-void dlg_listbox_addwithid(union control *ctrl, dlgparam *dp,
+void dlg_listbox_addwithid(dlgcontrol *ctrl, dlgparam *dp,
                            char const *text, int id)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
@@ -589,7 +589,7 @@ void dlg_listbox_addwithid(union control *ctrl, dlgparam *dp,
     dp->flags &= ~FLAG_UPDATING_COMBO_LIST;
 }
 
-int dlg_listbox_getid(union control *ctrl, dlgparam *dp, int index)
+int dlg_listbox_getid(dlgcontrol *ctrl, dlgparam *dp, int index)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
 
@@ -628,7 +628,7 @@ int dlg_listbox_getid(union control *ctrl, dlgparam *dp, int index)
 }
 
 /* dlg_listbox_index returns <0 if no single element is selected. */
-int dlg_listbox_index(union control *ctrl, dlgparam *dp)
+int dlg_listbox_index(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
 
@@ -712,7 +712,7 @@ int dlg_listbox_index(union control *ctrl, dlgparam *dp)
     return -1;                         /* placate dataflow analysis */
 }
 
-bool dlg_listbox_issel(union control *ctrl, dlgparam *dp, int index)
+bool dlg_listbox_issel(dlgcontrol *ctrl, dlgparam *dp, int index)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
 
@@ -769,7 +769,7 @@ bool dlg_listbox_issel(union control *ctrl, dlgparam *dp, int index)
     return false;                      /* placate dataflow analysis */
 }
 
-void dlg_listbox_select(union control *ctrl, dlgparam *dp, int index)
+void dlg_listbox_select(dlgcontrol *ctrl, dlgparam *dp, int index)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
 
@@ -837,7 +837,7 @@ void dlg_listbox_select(union control *ctrl, dlgparam *dp, int index)
     unreachable("bad control type in listbox_select");
 }
 
-void dlg_text_set(union control *ctrl, dlgparam *dp, char const *text)
+void dlg_text_set(dlgcontrol *ctrl, dlgparam *dp, char const *text)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
 
@@ -847,7 +847,7 @@ void dlg_text_set(union control *ctrl, dlgparam *dp, char const *text)
     gtk_label_set_text(GTK_LABEL(uc->text), text);
 }
 
-void dlg_label_change(union control *ctrl, dlgparam *dp, char const *text)
+void dlg_label_change(dlgcontrol *ctrl, dlgparam *dp, char const *text)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
 
@@ -885,7 +885,7 @@ void dlg_label_change(union control *ctrl, dlgparam *dp, char const *text)
     }
 }
 
-void dlg_filesel_set(union control *ctrl, dlgparam *dp, Filename *fn)
+void dlg_filesel_set(dlgcontrol *ctrl, dlgparam *dp, Filename *fn)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
     /* We must copy fn->path before passing it to gtk_entry_set_text.
@@ -897,7 +897,7 @@ void dlg_filesel_set(union control *ctrl, dlgparam *dp, Filename *fn)
     sfree(duppath);
 }
 
-Filename *dlg_filesel_get(union control *ctrl, dlgparam *dp)
+Filename *dlg_filesel_get(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
     assert(uc->ctrl->generic.type == CTRL_FILESELECT);
@@ -905,7 +905,7 @@ Filename *dlg_filesel_get(union control *ctrl, dlgparam *dp)
     return filename_from_str(gtk_entry_get_text(GTK_ENTRY(uc->entry)));
 }
 
-void dlg_fontsel_set(union control *ctrl, dlgparam *dp, FontSpec *fs)
+void dlg_fontsel_set(dlgcontrol *ctrl, dlgparam *dp, FontSpec *fs)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
     /* We must copy fs->name before passing it to gtk_entry_set_text.
@@ -917,7 +917,7 @@ void dlg_fontsel_set(union control *ctrl, dlgparam *dp, FontSpec *fs)
     sfree(dupname);
 }
 
-FontSpec *dlg_fontsel_get(union control *ctrl, dlgparam *dp)
+FontSpec *dlg_fontsel_get(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
     assert(uc->ctrl->generic.type == CTRL_FONTSELECT);
@@ -930,7 +930,7 @@ FontSpec *dlg_fontsel_get(union control *ctrl, dlgparam *dp)
  * cause the front end (if possible) to delay updating the screen
  * until it's all complete, thus avoiding flicker.
  */
-void dlg_update_start(union control *ctrl, dlgparam *dp)
+void dlg_update_start(dlgcontrol *ctrl, dlgparam *dp)
 {
     /*
      * Apparently we can't do this at all in GTK. GtkCList supports
@@ -938,7 +938,7 @@ void dlg_update_start(union control *ctrl, dlgparam *dp)
      */
 }
 
-void dlg_update_done(union control *ctrl, dlgparam *dp)
+void dlg_update_done(dlgcontrol *ctrl, dlgparam *dp)
 {
     /*
      * Apparently we can't do this at all in GTK. GtkCList supports
@@ -946,7 +946,7 @@ void dlg_update_done(union control *ctrl, dlgparam *dp)
      */
 }
 
-void dlg_set_focus(union control *ctrl, dlgparam *dp)
+void dlg_set_focus(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
 
@@ -1077,7 +1077,7 @@ void dlg_end(dlgparam *dp, int value)
     gtk_widget_destroy(dp->window);
 }
 
-void dlg_refresh(union control *ctrl, dlgparam *dp)
+void dlg_refresh(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct uctrl *uc;
 
@@ -1096,7 +1096,7 @@ void dlg_refresh(union control *ctrl, dlgparam *dp)
     }
 }
 
-void dlg_coloursel_start(union control *ctrl, dlgparam *dp, int r, int g, int b)
+void dlg_coloursel_start(dlgcontrol *ctrl, dlgparam *dp, int r, int g, int b)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
 
@@ -1181,7 +1181,7 @@ void dlg_coloursel_start(union control *ctrl, dlgparam *dp, int r, int g, int b)
     gtk_widget_show(coloursel);
 }
 
-bool dlg_coloursel_results(union control *ctrl, dlgparam *dp,
+bool dlg_coloursel_results(dlgcontrol *ctrl, dlgparam *dp,
                            int *r, int *g, int *b)
 {
     if (dp->coloursel_result.ok) {
@@ -1202,7 +1202,7 @@ static gboolean widget_focus(GtkWidget *widget, GdkEventFocus *event,
 {
     struct dlgparam *dp = (struct dlgparam *)data;
     struct uctrl *uc = dlg_find_bywidget(dp, widget);
-    union control *focus;
+    dlgcontrol *focus;
 
     if (uc && uc->ctrl)
         focus = uc->ctrl;
@@ -1877,7 +1877,7 @@ GtkWidget *layout_ctrls(
      * and add them to the Columns.
      */
     for (i = 0; i < s->ncontrols; i++) {
-        union control *ctrl = s->ctrls[i];
+        dlgcontrol *ctrl = s->ctrls[i];
         struct uctrl *uc;
         bool left = false;
         GtkWidget *w = NULL;
@@ -2576,7 +2576,7 @@ static void treeitem_sel(GtkItem *item, gpointer data)
 }
 #endif
 
-bool dlg_is_visible(union control *ctrl, dlgparam *dp)
+bool dlg_is_visible(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct uctrl *uc = dlg_find_byctrl(dp, ctrl);
     /*
@@ -3283,7 +3283,7 @@ static void dlgparam_destroy(GtkWidget *widget, gpointer data)
     sfree(dp);
 }
 
-static void messagebox_handler(union control *ctrl, dlgparam *dp,
+static void messagebox_handler(dlgcontrol *ctrl, dlgparam *dp,
                                void *data, int event)
 {
     if (event == EVENT_ACTION)
@@ -3312,7 +3312,7 @@ static GtkWidget *create_message_box_general(
 {
     GtkWidget *window, *w0, *w1;
     struct controlset *s0, *s1;
-    union control *c, *textctrl;
+    dlgcontrol *c, *textctrl;
     struct dlgparam *dp;
     struct Shortcuts scs;
     int i, index, ncols, min_type;
@@ -3888,7 +3888,7 @@ struct eventlog_stuff {
     struct controlbox *eventbox;
     struct Shortcuts scs;
     struct dlgparam dp;
-    union control *listctrl;
+    dlgcontrol *listctrl;
     char **events_initial;
     char **events_circular;
     int ninitial, ncircular, circular_first;
@@ -3905,13 +3905,13 @@ static void eventlog_destroy(GtkWidget *widget, gpointer data)
     dlg_cleanup(&es->dp);
     ctrl_free_box(es->eventbox);
 }
-static void eventlog_ok_handler(union control *ctrl, dlgparam *dp,
+static void eventlog_ok_handler(dlgcontrol *ctrl, dlgparam *dp,
                                 void *data, int event)
 {
     if (event == EVENT_ACTION)
         dlg_end(dp, 0);
 }
-static void eventlog_list_handler(union control *ctrl, dlgparam *dp,
+static void eventlog_list_handler(dlgcontrol *ctrl, dlgparam *dp,
                                   void *data, int event)
 {
     eventlog_stuff *es = (eventlog_stuff *)data;
@@ -4004,7 +4004,7 @@ void showeventlog(eventlog_stuff *es, void *parentwin)
     GtkWidget *window, *w0, *w1;
     GtkWidget *parent = GTK_WIDGET(parentwin);
     struct controlset *s0, *s1;
-    union control *c;
+    dlgcontrol *c;
     int index;
     char *title;
 
diff --git a/windows/config.c b/windows/config.c
index 17448260..4f6e6c5c 100644
--- a/windows/config.c
+++ b/windows/config.c
@@ -10,7 +10,7 @@
 #include "dialog.h"
 #include "storage.h"
 
-static void about_handler(union control *ctrl, dlgparam *dlg,
+static void about_handler(dlgcontrol *ctrl, dlgparam *dlg,
                           void *data, int event)
 {
     HWND *hwndp = (HWND *)ctrl->generic.context.p;
@@ -20,7 +20,7 @@ static void about_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void help_handler(union control *ctrl, dlgparam *dlg,
+static void help_handler(dlgcontrol *ctrl, dlgparam *dlg,
                          void *data, int event)
 {
     HWND *hwndp = (HWND *)ctrl->generic.context.p;
@@ -30,7 +30,7 @@ static void help_handler(union control *ctrl, dlgparam *dlg,
     }
 }
 
-static void variable_pitch_handler(union control *ctrl, dlgparam *dlg,
+static void variable_pitch_handler(dlgcontrol *ctrl, dlgparam *dlg,
                                    void *data, int event)
 {
     if (event == EVENT_REFRESH) {
@@ -46,7 +46,7 @@ void win_setup_config_box(struct controlbox *b, HWND *hwndp, bool has_help,
     const struct BackendVtable *backvt;
     bool resize_forbidden = false;
     struct controlset *s;
-    union control *c;
+    dlgcontrol *c;
     char *str;
 
     if (!midsession) {
@@ -91,7 +91,7 @@ void win_setup_config_box(struct controlbox *b, HWND *hwndp, bool has_help,
                 if (i < s->ncontrols-2) {
                     c = s->ctrls[s->ncontrols-1];
                     memmove(s->ctrls+i+2, s->ctrls+i+1,
-                            (s->ncontrols-i-2)*sizeof(union control *));
+                            (s->ncontrols-i-2)*sizeof(dlgcontrol *));
                     s->ctrls[i+1] = c;
                 }
                 break;
@@ -296,7 +296,7 @@ void win_setup_config_box(struct controlbox *b, HWND *hwndp, bool has_help,
      * up...
      */
     c = s->ctrls[s->ncontrols-1];      /* this should be the new control */
-    memmove(s->ctrls+1, s->ctrls, (s->ncontrols-1)*sizeof(union control *));
+    memmove(s->ctrls+1, s->ctrls, (s->ncontrols-1)*sizeof(dlgcontrol *));
     s->ctrls[0] = c;
 
     /*
diff --git a/windows/controls.c b/windows/controls.c
index 51d0921b..7543eb13 100644
--- a/windows/controls.c
+++ b/windows/controls.c
@@ -1250,7 +1250,7 @@ static int winctrl_cmp_byid(void *av, void *bv)
 }
 static int winctrl_cmp_byctrl_find(void *av, void *bv)
 {
-    union control *a = (union control *)av;
+    dlgcontrol *a = (dlgcontrol *)av;
     struct winctrl *b = (struct winctrl *)bv;
     if (a < b->ctrl)
         return -1;
@@ -1310,7 +1310,7 @@ void winctrl_remove(struct winctrls *wc, struct winctrl *c)
     assert(ret == c);
 }
 
-struct winctrl *winctrl_findbyctrl(struct winctrls *wc, union control *ctrl)
+struct winctrl *winctrl_findbyctrl(struct winctrls *wc, dlgcontrol *ctrl)
 {
     return find234(wc->byctrl, ctrl, winctrl_cmp_byctrl_find);
 }
@@ -1354,7 +1354,7 @@ void winctrl_layout(struct dlgparam *dp, struct winctrls *wc,
     int ncols, colstart, colspan;
 
     struct ctlpos tabdelays[16];
-    union control *tabdelayed[16];
+    dlgcontrol *tabdelayed[16];
     int ntabdelays;
 
     struct ctlpos pos;
@@ -1402,7 +1402,7 @@ void winctrl_layout(struct dlgparam *dp, struct winctrls *wc,
 
     /* Loop over each control in the controlset. */
     for (i = 0; i < s->ncontrols; i++) {
-        union control *ctrl = s->ctrls[i];
+        dlgcontrol *ctrl = s->ctrls[i];
 
         /*
          * Generic processing that pertains to all control types.
@@ -1761,7 +1761,7 @@ void winctrl_layout(struct dlgparam *dp, struct winctrls *wc,
         endbox(cp);
 }
 
-static void winctrl_set_focus(union control *ctrl, struct dlgparam *dp,
+static void winctrl_set_focus(dlgcontrol *ctrl, struct dlgparam *dp,
                               bool has_focus)
 {
     if (has_focus) {
@@ -1774,7 +1774,7 @@ static void winctrl_set_focus(union control *ctrl, struct dlgparam *dp,
     }
 }
 
-union control *dlg_last_focused(union control *ctrl, dlgparam *dp)
+dlgcontrol *dlg_last_focused(dlgcontrol *ctrl, dlgparam *dp)
 {
     return dp->focused == ctrl ? dp->lastfocused : dp->focused;
 }
@@ -1787,7 +1787,7 @@ bool winctrl_handle_command(struct dlgparam *dp, UINT msg,
                             WPARAM wParam, LPARAM lParam)
 {
     struct winctrl *c;
-    union control *ctrl;
+    dlgcontrol *ctrl;
     int i, id;
     bool ret;
     static UINT draglistmsg = WM_NULL;
@@ -2107,7 +2107,7 @@ bool winctrl_context_help(struct dlgparam *dp, HWND hwnd, int id)
  * mechanism can call to access the dialog box entries.
  */
 
-static struct winctrl *dlg_findbyctrl(struct dlgparam *dp, union control *ctrl)
+static struct winctrl *dlg_findbyctrl(struct dlgparam *dp, dlgcontrol *ctrl)
 {
     int i;
 
@@ -2119,7 +2119,7 @@ static struct winctrl *dlg_findbyctrl(struct dlgparam *dp, union control *ctrl)
     return NULL;
 }
 
-bool dlg_is_visible(union control *ctrl, dlgparam *dp)
+bool dlg_is_visible(dlgcontrol *ctrl, dlgparam *dp)
 {
     /*
      * In this implementation of the dialog box, we physically
@@ -2130,7 +2130,7 @@ bool dlg_is_visible(union control *ctrl, dlgparam *dp)
     return dlg_findbyctrl(dp, ctrl) != NULL;
 }
 
-void dlg_radiobutton_set(union control *ctrl, dlgparam *dp, int whichbutton)
+void dlg_radiobutton_set(dlgcontrol *ctrl, dlgparam *dp, int whichbutton)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     assert(c && c->ctrl->generic.type == CTRL_RADIO);
@@ -2140,7 +2140,7 @@ void dlg_radiobutton_set(union control *ctrl, dlgparam *dp, int whichbutton)
                      c->base_id + 1 + whichbutton);
 }
 
-int dlg_radiobutton_get(union control *ctrl, dlgparam *dp)
+int dlg_radiobutton_get(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     int i;
@@ -2151,28 +2151,28 @@ int dlg_radiobutton_get(union control *ctrl, dlgparam *dp)
     unreachable("no radio button was checked");
 }
 
-void dlg_checkbox_set(union control *ctrl, dlgparam *dp, bool checked)
+void dlg_checkbox_set(dlgcontrol *ctrl, dlgparam *dp, bool checked)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     assert(c && c->ctrl->generic.type == CTRL_CHECKBOX);
     CheckDlgButton(dp->hwnd, c->base_id, checked);
 }
 
-bool dlg_checkbox_get(union control *ctrl, dlgparam *dp)
+bool dlg_checkbox_get(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     assert(c && c->ctrl->generic.type == CTRL_CHECKBOX);
     return 0 != IsDlgButtonChecked(dp->hwnd, c->base_id);
 }
 
-void dlg_editbox_set(union control *ctrl, dlgparam *dp, char const *text)
+void dlg_editbox_set(dlgcontrol *ctrl, dlgparam *dp, char const *text)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     assert(c && c->ctrl->generic.type == CTRL_EDITBOX);
     SetDlgItemText(dp->hwnd, c->base_id+1, text);
 }
 
-char *dlg_editbox_get(union control *ctrl, dlgparam *dp)
+char *dlg_editbox_get(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     assert(c && c->ctrl->generic.type == CTRL_EDITBOX);
@@ -2180,7 +2180,7 @@ char *dlg_editbox_get(union control *ctrl, dlgparam *dp)
 }
 
 /* The `listbox' functions can also apply to combo boxes. */
-void dlg_listbox_clear(union control *ctrl, dlgparam *dp)
+void dlg_listbox_clear(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     int msg;
@@ -2193,7 +2193,7 @@ void dlg_listbox_clear(union control *ctrl, dlgparam *dp)
     SendDlgItemMessage(dp->hwnd, c->base_id+1, msg, 0, 0);
 }
 
-void dlg_listbox_del(union control *ctrl, dlgparam *dp, int index)
+void dlg_listbox_del(dlgcontrol *ctrl, dlgparam *dp, int index)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     int msg;
@@ -2206,7 +2206,7 @@ void dlg_listbox_del(union control *ctrl, dlgparam *dp, int index)
     SendDlgItemMessage(dp->hwnd, c->base_id+1, msg, index, 0);
 }
 
-void dlg_listbox_add(union control *ctrl, dlgparam *dp, char const *text)
+void dlg_listbox_add(dlgcontrol *ctrl, dlgparam *dp, char const *text)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     int msg;
@@ -2226,7 +2226,7 @@ void dlg_listbox_add(union control *ctrl, dlgparam *dp, char const *text)
  * strings in any listbox then you MUST not assign them different
  * IDs and expect to get meaningful results back.
  */
-void dlg_listbox_addwithid(union control *ctrl, dlgparam *dp,
+void dlg_listbox_addwithid(dlgcontrol *ctrl, dlgparam *dp,
                            char const *text, int id)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
@@ -2243,7 +2243,7 @@ void dlg_listbox_addwithid(union control *ctrl, dlgparam *dp,
     SendDlgItemMessage(dp->hwnd, c->base_id+1, msg2, index, (LPARAM)id);
 }
 
-int dlg_listbox_getid(union control *ctrl, dlgparam *dp, int index)
+int dlg_listbox_getid(dlgcontrol *ctrl, dlgparam *dp, int index)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     int msg;
@@ -2254,7 +2254,7 @@ int dlg_listbox_getid(union control *ctrl, dlgparam *dp, int index)
 }
 
 /* dlg_listbox_index returns <0 if no single element is selected. */
-int dlg_listbox_index(union control *ctrl, dlgparam *dp)
+int dlg_listbox_index(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     int msg, ret;
@@ -2273,7 +2273,7 @@ int dlg_listbox_index(union control *ctrl, dlgparam *dp)
         return ret;
 }
 
-bool dlg_listbox_issel(union control *ctrl, dlgparam *dp, int index)
+bool dlg_listbox_issel(dlgcontrol *ctrl, dlgparam *dp, int index)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     assert(c && c->ctrl->generic.type == CTRL_LISTBOX &&
@@ -2283,7 +2283,7 @@ bool dlg_listbox_issel(union control *ctrl, dlgparam *dp, int index)
         SendDlgItemMessage(dp->hwnd, c->base_id+1, LB_GETSEL, index, 0);
 }
 
-void dlg_listbox_select(union control *ctrl, dlgparam *dp, int index)
+void dlg_listbox_select(dlgcontrol *ctrl, dlgparam *dp, int index)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     int msg;
@@ -2293,14 +2293,14 @@ void dlg_listbox_select(union control *ctrl, dlgparam *dp, int index)
     SendDlgItemMessage(dp->hwnd, c->base_id+1, msg, index, 0);
 }
 
-void dlg_text_set(union control *ctrl, dlgparam *dp, char const *text)
+void dlg_text_set(dlgcontrol *ctrl, dlgparam *dp, char const *text)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     assert(c && c->ctrl->generic.type == CTRL_TEXT);
     SetDlgItemText(dp->hwnd, c->base_id, text);
 }
 
-void dlg_label_change(union control *ctrl, dlgparam *dp, char const *text)
+void dlg_label_change(dlgcontrol *ctrl, dlgparam *dp, char const *text)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     char *escaped = NULL;
@@ -2345,14 +2345,14 @@ void dlg_label_change(union control *ctrl, dlgparam *dp, char const *text)
     }
 }
 
-void dlg_filesel_set(union control *ctrl, dlgparam *dp, Filename *fn)
+void dlg_filesel_set(dlgcontrol *ctrl, dlgparam *dp, Filename *fn)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     assert(c && c->ctrl->generic.type == CTRL_FILESELECT);
     SetDlgItemText(dp->hwnd, c->base_id+1, fn->path);
 }
 
-Filename *dlg_filesel_get(union control *ctrl, dlgparam *dp)
+Filename *dlg_filesel_get(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     char *tmp;
@@ -2364,7 +2364,7 @@ Filename *dlg_filesel_get(union control *ctrl, dlgparam *dp)
     return ret;
 }
 
-void dlg_fontsel_set(union control *ctrl, dlgparam *dp, FontSpec *fs)
+void dlg_fontsel_set(dlgcontrol *ctrl, dlgparam *dp, FontSpec *fs)
 {
     char *buf, *boldstr;
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
@@ -2386,7 +2386,7 @@ void dlg_fontsel_set(union control *ctrl, dlgparam *dp, FontSpec *fs)
     dlg_auto_set_fixed_pitch_flag(dp);
 }
 
-FontSpec *dlg_fontsel_get(union control *ctrl, dlgparam *dp)
+FontSpec *dlg_fontsel_get(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     assert(c && c->ctrl->generic.type == CTRL_FONTSELECT);
@@ -2398,7 +2398,7 @@ FontSpec *dlg_fontsel_get(union control *ctrl, dlgparam *dp)
  * cause the front end (if possible) to delay updating the screen
  * until it's all complete, thus avoiding flicker.
  */
-void dlg_update_start(union control *ctrl, dlgparam *dp)
+void dlg_update_start(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     if (c && c->ctrl->generic.type == CTRL_LISTBOX) {
@@ -2406,7 +2406,7 @@ void dlg_update_start(union control *ctrl, dlgparam *dp)
     }
 }
 
-void dlg_update_done(union control *ctrl, dlgparam *dp)
+void dlg_update_done(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     if (c && c->ctrl->generic.type == CTRL_LISTBOX) {
@@ -2416,7 +2416,7 @@ void dlg_update_done(union control *ctrl, dlgparam *dp)
     }
 }
 
-void dlg_set_focus(union control *ctrl, dlgparam *dp)
+void dlg_set_focus(dlgcontrol *ctrl, dlgparam *dp)
 {
     struct winctrl *c = dlg_findbyctrl(dp, ctrl);
     int id;
@@ -2474,7 +2474,7 @@ void dlg_end(dlgparam *dp, int value)
     dp->endresult = value;
 }
 
-void dlg_refresh(union control *ctrl, dlgparam *dp)
+void dlg_refresh(dlgcontrol *ctrl, dlgparam *dp)
 {
     int i, j;
     struct winctrl *c;
@@ -2501,7 +2501,7 @@ void dlg_refresh(union control *ctrl, dlgparam *dp)
     }
 }
 
-void dlg_coloursel_start(union control *ctrl, dlgparam *dp, int r, int g, int b)
+void dlg_coloursel_start(dlgcontrol *ctrl, dlgparam *dp, int r, int g, int b)
 {
     dp->coloursel_wanted = true;
     dp->coloursel_result.r = r;
@@ -2509,7 +2509,7 @@ void dlg_coloursel_start(union control *ctrl, dlgparam *dp, int r, int g, int b)
     dp->coloursel_result.b = b;
 }
 
-bool dlg_coloursel_results(union control *ctrl, dlgparam *dp,
+bool dlg_coloursel_results(dlgcontrol *ctrl, dlgparam *dp,
                            int *r, int *g, int *b)
 {
     if (dp->coloursel_result.ok) {
diff --git a/windows/platform.h b/windows/platform.h
index 25de278f..11103511 100644
--- a/windows/platform.h
+++ b/windows/platform.h
@@ -413,7 +413,7 @@ struct dlgparam {
     char *wintitle;                    /* title of actual window */
     char *errtitle;                    /* title of error sub-messageboxes */
     void *data;                        /* data to pass in refresh events */
-    union control *focused, *lastfocused; /* which ctrl has focus now/before */
+    dlgcontrol *focused, *lastfocused; /* which ctrl has focus now/before */
     bool shortcuts[128];               /* track which shortcuts in use */
     bool coloursel_wanted;             /* has an event handler asked for
                                         * a colour selector? */
@@ -490,11 +490,11 @@ void dlg_set_fixed_pitch_flag(dlgparam *dlg, bool flag);
 #define MAX_SHORTCUTS_PER_CTRL 16
 
 /*
- * This structure is what's stored for each `union control' in the
+ * This structure is what's stored for each `dlgcontrol' in the
  * portable-dialog interface.
  */
 struct winctrl {
-    union control *ctrl;
+    dlgcontrol *ctrl;
     /*
      * The control may have several components at the Windows
      * level, with different dialog IDs. To avoid needing N
@@ -525,7 +525,7 @@ struct winctrl {
 };
 /*
  * And this structure holds a set of the above, in two separate
- * tree234s so that it can find an item by `union control' or by
+ * tree234s so that it can find an item by `dlgcontrol' or by
  * dialog ID.
  */
 struct winctrls {
@@ -538,7 +538,7 @@ void winctrl_init(struct winctrls *);
 void winctrl_cleanup(struct winctrls *);
 void winctrl_add(struct winctrls *, struct winctrl *);
 void winctrl_remove(struct winctrls *, struct winctrl *);
-struct winctrl *winctrl_findbyctrl(struct winctrls *, union control *);
+struct winctrl *winctrl_findbyctrl(struct winctrls *, dlgcontrol *);
 struct winctrl *winctrl_findbyid(struct winctrls *, int);
 struct winctrl *winctrl_findbyindex(struct winctrls *, int);
 void winctrl_layout(struct dlgparam *dp, struct winctrls *wc,