There's a really handy feature in Autodesk Sketchbook that I think would be perfect for FlipaClip. Double tapping each corner activates a shortcut. You can select which shortcut is set to which corner in the preferences menu.
I have mine set to Undo, Redo, Clear Layer and 100% Zoom - and I often find myself tapping the corners when drawing in FlipaClip, before realising that it won't work in this app!
If, in a future release of FlipaClip, there is an option to turn off toolbars for a full screen drawing layout, then a customisable corner shortcuts feature would be perfect.