Avoid copying lists during draw
Avoid copying lists during draw

We can use gdk_window_peek_children here, instead of copying
the list. Note that we preserve the bottom-to-top ordering by
iterating the list from the end.
gdk_window_get_children_with_user_data was doing a list
reversal while filtering the list.

alexlarsson/gtk,alexlarsson/gtk,alexlarsson/gtk,grubersjoe/adwaita,alexlarsson/gtk,grubersjoe/adwaita,grubersjoe/adwaita,alexlarsson/gtk,alexlarsson/gtk,alexlarsson/gtk,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,alexlarsson/gtk,grubersjoe/adwaita