Invoke child_removed on the proxy even if the child proxy is destroyed.
Handle child events on the QtFlowItem
Handle child events on the QtMainWindow
Call super on the child event if not otherwise handled
Update the Mdi child event handling
Always unparent the object during destruction
Handle child events on a QtMenu
Allow and integer index to insert_children() in addition to an Object
Update child event handling for QtMenuBar. Standardize widget creation.