GtkTheme: Menu border-radius and box-shadow changes
- introduce $menu_radius
- use it for menus and context-menus
- use the popover box-shadow also for menus
- use padding for menus to avoid edge overlapping
- remove the background for menus to avoid bleeding out of the round edges
See: !432 (merged)
Top-menu "first instance":
Context-menu and all "childs" spawned out of the "top menu first instance":
