a174c18fb5
Frames are painted on the frame window according to the GTK+ theme. Depending on the target's visual, this means either drawing over a black destination or a fully transparent one. So in cases where the theme doesn't paint decorations with full opacity, decorations for windows with an rgba visual look different from those with a non-rgba visual. Using an rgba visual for all frames independent from the client's visual can potentially break clients, so our only option for a consistent appearance is to explicitly initialize the frame background to black before painting the theme's decoration on top. https://bugzilla.gnome.org/show_bug.cgi?id=745060