X11 backend doesn't, and for good reason - main code body does not check
that the window it sets opacity for is, in fact, toplevel.
Just silently fail to do anything for non-toplevel windows.
https://bugzilla.gnome.org/show_bug.cgi?id=733769
PFN_SetLayeredWindowAttributes setLayeredWindowAttributes = NULL;
g_return_if_fail (GDK_IS_WINDOW (window));
- g_return_if_fail (WINDOW_IS_TOPLEVEL (window));
- if (GDK_WINDOW_DESTROYED (window))
+ if (!WINDOW_IS_TOPLEVEL (window) || GDK_WINDOW_DESTROYED (window))
return;
if (opacity < 0)