This reverts commit
fb9a6bb6d8d6b60b25c9b9853decbcea938f7863.
In a recent test, I've found that Xfce and Mate now support
this, so they will not be affected by this requirement. And
adding the check back will solve the 'client-side shadow'
problem in KDE.
if (!gdk_screen_is_composited (screen))
return FALSE;
+ if (!gdk_x11_screen_supports_net_wm_hint (screen, gdk_atom_intern_static_string ("_GTK_FRAME_EXTENTS")))
+ return FALSE;
+
/* We need a visual with alpha */
visual = gdk_screen_get_rgba_visual (screen);
if (!visual)