Add sub-editor types in the editor menu

Some editors have sub-editor types, for example the Graph Editor, which has the F-Curve View, and the Driver View. If you want to switch to the Driver view, you have to switch to the Graph Editor, then switch the view to Drivers. It would be a lot more convenient to be able to switch directly to the Driver editor.

The sub-editors could appear as a flyout menu that appears after a short delay. If you click on the main menu-item, you would get the default view, otherwise you can choose from the submenus.

Alternately, they could perhaps appear without a flyout, slightly indented to indicate they're sub-views.