Fix selection with mouse in multi-monitor alt-tab dialog

Bug: 10966

Signed-off-by: Olivier Fourdan <fourdan@xfce.org>
Fix gtk frame extents updates

So that tiling works with CSD from GTK/GNOME.

Signed-off-by: Olivier Fourdan <fourdan@xfce.org>
Allow color substitution in themerc

The idea is to be able to substitute colors
by another, e.g.:

  active_text_color=active_text_color_2
  active_text_shadow_color=active_hilight_2

This gives a lot more flexibility in color themes
based on GTK colors.

Signed-off-by: Olivier Fourdan <fourdan@xfce.org>
Use color substitution in default themes

So that it's usable with dark gtk themes as well.

Signed-off-by: Olivier Fourdan <fourdan@xfce.org>