Y20260519-1000
On Gtk 4, PaintListener on leaf controls (Button, Label, etc.) drew custom content under the native widget appearance instead of over it (issue #2819). Fixing this by simply moving snapshotToDraw after the children loop regressed JFace Forms rendering (PR #3299). New paint-ordering scheme that mirrors Gtk 3's signal split (EXPOSE_EVENT_INVERSE for containers, DRAW/EXPOSE_EVENT for leaf controls).