
We currently only ignore minimized windows, not windows that are
hidden for other reasons - namely on wayland windows are initially
hidden until they are placed.
This fixes a flicker in the transparent top bar on wayland when the
"position" of an unplaced window wrongly suggests the window is
overlapping the top bar.
https://gitlab.gnome.org/GNOME/gnome-shell/issues/693
(cherry-picked from commit a0dc8dc7ef
)