Use gtkcompat.h to slim down a few ifdefs.

Now that I've got a general place to centralise handling of at least
the simple differences between GTK 1 and 2, I should use it wherever
possible. So this commit removes just a small number of ifdefs which
are either obsoleted by definitions already in gtkcompat.h (like
set_size_request vs set_usize), or can easily be replaced by adding
another (e.g. gtk_color_selection_set_has_opacity_control).

unix/gtkcompat.h

@@ -40,6 +40,8 @@
 #define gtk_widget_set_size_request gtk_widget_set_usize
 #define gtk_radio_button_get_group gtk_radio_button_group
 #define gtk_notebook_set_current_page gtk_notebook_set_page
+#define gtk_color_selection_set_has_opacity_control \
+    gtk_color_selection_set_opacity
 
 #define gtk_dialog_get_content_area(dlg) ((dlg)->vbox)
 #define gtk_dialog_get_action_area(dlg) ((dlg)->action_area)

unix/gtkdlg.c

@@ -1143,11 +1143,7 @@ void dlg_coloursel_start(union control *ctrl, void *dlg, int r, int g, int b)
     dp->coloursel_result.ok = FALSE;
 
     gtk_window_set_modal(GTK_WINDOW(coloursel), TRUE);
-#if GTK_CHECK_VERSION(2,0,0)
     gtk_color_selection_set_has_opacity_control(cs, FALSE);
-#else
-    gtk_color_selection_set_opacity(cs, FALSE);
-#endif
 
 #if GTK_CHECK_VERSION(2,0,0)
     {

unix/gtkfont.c

@@ -2562,11 +2562,9 @@ unifontsel *unifontsel_new(const char *wintitle)
 	gtk_label_set_text(GTK_LABEL(label), "48000");
 	gtk_widget_size_request(label, &req);
 	size_width = req.width;
-#if GTK_CHECK_VERSION(2,10,0)
-	g_object_ref_sink(label);
-	g_object_unref(label);
-#else
         g_object_ref_sink(G_OBJECT(label));
+#if GTK_CHECK_VERSION(2,10,0)
+	g_object_unref(label);
 #endif
     }
 

unix/gtkwin.c

@@ -1639,11 +1639,7 @@ void request_resize(void *frontend, int w, int h)
     large_x += 32;
     large_y += 32;
 
-#if GTK_CHECK_VERSION(2,0,0)
     gtk_widget_set_size_request(inst->area, large_x, large_y);
-#else
-    gtk_widget_set_usize(inst->area, large_x, large_y);
-#endif
     gtk_widget_size_request(inst->area, &inner);
     gtk_widget_size_request(inst->window, &outer);
 
@@ -1659,12 +1655,11 @@ void request_resize(void *frontend, int w, int h)
      * way to do this, I think, is to set it to what the size is
      * really going to end up being.
      */
-#if GTK_CHECK_VERSION(2,0,0)
     gtk_widget_set_size_request(inst->area, area_x, area_y);
+#if GTK_CHECK_VERSION(2,0,0)
     gtk_window_resize(GTK_WINDOW(inst->window),
 		      area_x + offset_x, area_y + offset_y);
 #else
-    gtk_widget_set_usize(inst->area, area_x, area_y);
     gtk_drawing_area_size(GTK_DRAWING_AREA(inst->area), area_x, area_y);
     /*
      * I can no longer remember what this call to