5d2b7e2c9e
Allow opening a popup menu from another menu. While the child menu is open, events on the parent menu are blocked. The parent menu is kept open when the child menu is closed; the child menu on the other hand is closed with the parent, e.g. when the focus moves to another toplevel menu. This feature will be used to implement combo box menu items. https://bugzilla.gnome.org/show_bug.cgi?id=652837