[mutter] screen: Don't map the COW on Wayland

[Jasper St. Pierre <jstpierre src gnome org>]

commit 0ac2f61a2c07d94a2d1b377a43feb72a7fe8098c
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Wed Feb 18 11:16:52 2015 -0800

    screen: Don't map the COW on Wayland
    
    This is unnecessary, and since we don't shape it, we get a giant input
    window covering the rest of our windows.

 src/core/screen.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/src/core/screen.c b/src/core/screen.c
index 582d757..e515072 100644
--- a/src/core/screen.c
+++ b/src/core/screen.c
@@ -678,7 +678,10 @@ meta_screen_new (MetaDisplay *display,
   screen->starting_corner = META_SCREEN_TOPLEFT;
   screen->guard_window = None;
 
-  screen->composite_overlay_window = XCompositeGetOverlayWindow (xdisplay, xroot);
+  /* If we're a Wayland compositor, then we don't grab the COW, since it
+   * will map it. */
+  if (!meta_is_wayland_compositor ())
+    screen->composite_overlay_window = XCompositeGetOverlayWindow (xdisplay, xroot);
 
   /* Now that we've gotten taken a reference count on the COW, we
    * can close the helper that is holding on to it */