GladePopup: Clear add item when adding as toplevel
Previously, if you chose a widget and used the "Add widget as toplevel" menu item, it would add the widget as a toplevel, but keep it as the "add item" on your cursor, which is annoying.
Previously, if you chose a widget and used the "Add widget as toplevel" menu item, it would add the widget as a toplevel, but keep it as the "add item" on your cursor, which is annoying.