[metacity/gnome-3-22] tile-preview: avoid deprecated gtk_widget_is_composited

[Alberts Muktupāvels <muktupavels src gnome org>]

commit ab8bd4792c7b3e1d3a4e2a1e276071ff49edbada
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Wed Nov 9 18:05:59 2016 +0200

    tile-preview: avoid deprecated gtk_widget_is_composited

 src/ui/tile-preview.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/ui/tile-preview.c b/src/ui/tile-preview.c
index 6d46256..1690e10 100644
--- a/src/ui/tile-preview.c
+++ b/src/ui/tile-preview.c
@@ -125,7 +125,7 @@ meta_tile_preview_composited_changed (GtkWidget *widget,
   GdkScreen *screen = gdk_screen_get_default ();
   GdkVisual *visual = gdk_screen_get_rgba_visual (screen);
 
-  preview->has_alpha = visual && gtk_widget_is_composited (widget);
+  preview->has_alpha = visual && gdk_screen_is_composited (screen);
 }
 
 MetaTilePreview *