Periodically, a very helpful button ("Edit ParentClass method") appears on the toolbar when editing an instance of a class (inside a form, for example). It seems to appear sporadically; it certainly doesn't come up everytime I'm editing the method code of an inherited object. If it doesn't appear, there doesn't seem to be any option for adding such a button to a toolbar.

Where does this button live? Is there any way to get it to appear consistently?