Update the ComboBox definitions
Update DockPane definitions
Add show/hide methods to Widget
Update Window for new base class methods
Fix attribute name typo
Fix typo
update docs
Create a list of items intead of a tuple
Fix bug with testing of flag values
Use a function to filter children instead of a property.
Update the cached property handling
move common code to the base class. Add a proxy active flag.
Use the proxy active flag. Change central widget property to function.
Only use the proxy if it is active.
Use a function for finding the child menu instead of a property.
Only communicate with an active proxy.
Update child event handling
Convert menu items property into a function
Convert the dock_widget property into a function
Update the MenuBar definitions