frames: apply modified hack from Mutter/Metacity

- this will be needed for proper window decoration color updates on theme change
  when theme variants fixes are applied

- realize/unrealize functions are dropped instead of map/unmap ones, because
  we didn't change these during GTK+3 porting

- MetaFrames now has GtkWindow as parent instead of GtkInvisible, otherwise
  the hack doesn't work (revert part of 96c7256d638b8c76c8abf786ba307e82a595dd67)

adapted from:
https://github.com/GNOME/metacity/commit/ba8500663457ad9f18ebfdf405162c2cb5caf88f

1 files changed, 6 insertions, 3 deletions

diff --git a/src/ui/ui.c b/src/ui/ui.c
index c805869f..9c99552d 100644
--- a/src/ui/ui.c
+++ b/src/ui/ui.c
@@ -271,9 +271,12 @@ meta_ui_new (Display *xdisplay,
 
   g_assert (xdisplay == GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()));
   ui->frames = meta_frames_new ();
-  /* This does not actually show any widget. MetaFrames has been hacked so
-   * that showing it doesn't actually do anything. But we need the flags
-   * set for GTK to deliver events properly. */
+  /* GTK+ needs the frame-sync protocol to work in order to properly
+   * handle style changes. This means that the dummy widget we create
+   * to get the style for title bars actually needs to be mapped
+   * and fully tracked as a MetaWindow. Horrible, but mostly harmless -
+   * the window is a 1x1 overide redirect window positioned offscreen.
+   */
   gtk_widget_show (GTK_WIDGET (ui->frames));
 
   g_object_set_data (G_OBJECT (gdisplay), "meta-ui", ui);