I had an idea for making it easier to switch between abilities, which is currently a pain: Simply put, what if there was a popup window, the same size and shape as the inventory window (well, technically one row taller) that would contain ALL currently unlocked class abilities, and which, like the inventory window could be kept permanently open if desired and freely moved around the screen) Alternately or possibly additionally it would be nice to be able to select your active ability from the skill tome/levelup window.
While this sounds like a really excellent idea, I seem to recall somewhere that tinkering with the UI tends to cause Nicholas epileptic fits. It's more arcane than the United States Internal Revenue Service's handbook. So not sure it's gonna happen.
Reasonable idea that is probably impractical to implement for a while yet. Also, I enjoy the metaphor and simile regarding the Dredmor UI code.