I just completed some editing a few minutes ago and something was bothering me. As you described, it was the constant switching in and out of the editor.
One thing that really brings this to light for me… When you edit multiple Parts in the Key Editor, it is always -very- clear which Part one is working on. The Key Editor obviously has no problem managing multiple Parts. So it shouldn’t be -that- hard for the developers to simply add the facility to split Parts -inside- the Key Editor… the code for doing the management is already in place.