Allow setting the WM_CLASS X window property as a configuration option

in saved sessions, so that a programmable window manager can
distinguish different PuTTYs/pterms on startup and assign them
different window management properties.

[originally from svn r9078]

unix/gtkcfg.c

@@ -127,4 +127,18 @@ void gtk_setup_config_box(struct controlbox *b, int midsession, void *win)
 		  HELPCTX(translation_utf8_override),
 		  dlg_stdcheckbox_handler,
 		  I(offsetof(Config,utf8_override)));
+
+    if (!midsession) {
+        /*
+         * Allow the user to specify the window class as part of the saved
+         * configuration, so that they can have their window manager treat
+         * different kinds of PuTTY and pterm differently if they want to.
+         */
+        s = ctrl_getset(b, "Window/Behaviour", "x11",
+                        "X Window System settings");
+        ctrl_editbox(s, "Window class name:", 'z', 50,
+                     HELPCTX(no_help), dlg_stdeditbox_handler,
+                     I(offsetof(Config,winclass)),
+                     I(sizeof(((Config *)0)->winclass)));
+    }
 }

unix/gtkwin.c

@@ -3430,6 +3430,9 @@ int pt_main(int argc, char **argv)
     init_cutbuffers();
 
     inst->window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
+    if (inst->cfg.winclass[0])
+        gtk_window_set_wmclass(GTK_WINDOW(inst->window),
+                               inst->cfg.winclass, inst->cfg.winclass);
 
     /*
      * Set up the colour map.