Select the first visible or selectable child of the menu shell; don't select tearoff items unless the only item is a tearoff item. Since 2.2
if TRUE, search for the first selectable menu item, otherwise select nothing if the first item isn't sensitive. This should be FALSE if the menu is being popped up initially.
See Implementation
Select the first visible or selectable child of the menu shell; don't select tearoff items unless the only item is a tearoff item. Since 2.2