The menu associated with a menubutton must be a child widget of the menubutton. Similarly, the menu for a cascade menu entry must be a child of the menu.
The @y index for a menu always returns a valid index, even if the mouse cursor is outside any entry. In this case, it simply returns the index of the closest entry, instead of none.
The selector attribute is now selectColor.
The postcascade operation posts the menu of a cascade entry:
$menu postcascade index
The insert operation adds a menu entry before a specified entry:
$menu insert index type options...