Move more functions into the new gtkmisc.c.

Several utility functions I've written over the last few weeks were in
rather random places because I didn't have a central gtkmisc.c to put
them in. Now I've got one, put them there!

unix/gtkfont.c

@@ -23,6 +23,7 @@
 #include "putty.h"
 #include "gtkfont.h"
 #include "gtkcompat.h"
+#include "gtkmisc.h"
 #include "tree234.h"
 
 #ifndef NOT_X_WINDOWS
@@ -1992,46 +1993,6 @@ static void multifont_draw_text(unifont_drawctx *ctx, unifont *font, int x,
     }
 }
 
-/* ----------------------------------------------------------------------
- * Utility routine used by the code below, and also gtkdlg.c.
- */
-
-void get_label_text_dimensions(const char *text, int *width, int *height)
-{
-    /*
-     * Determine the dimensions of a piece of text in the standard
-     * font used in GTK interface elements like labels. We do this by
-     * instantiating an actual GtkLabel, and then querying its size.
-     *
-     * But GTK2 and GTK3 require us to query the size completely
-     * differently. I'm sure there ought to be an easier approach than
-     * the way I'm doing this in GTK3, too!
-     */
-    GtkWidget *label = gtk_label_new(text);
-
-#if GTK_CHECK_VERSION(3,0,0)
-    PangoLayout *layout = gtk_label_get_layout(GTK_LABEL(label));
-    PangoRectangle logrect;
-    pango_layout_get_extents(layout, NULL, &logrect);
-    if (width)
-        *width = logrect.width / PANGO_SCALE;
-    if (height)
-        *height = logrect.height / PANGO_SCALE;
-#else
-    GtkRequisition req;
-    gtk_widget_size_request(label, &req);
-    if (width)
-        *width = req.width;
-    if (height)
-        *height = req.height;
-#endif
-
-    g_object_ref_sink(G_OBJECT(label));
-#if GTK_CHECK_VERSION(2,10,0)
-    g_object_unref(label);
-#endif
-}
-
 #if GTK_CHECK_VERSION(2,0,0)
 
 /* ----------------------------------------------------------------------