I love Photoshop, I really do. But there's one quirk that drives me up the wall: Undo versus Step Backward.

Photoshop's Undo works like no other Undo I've ever known. Basically, the same hotkey, Ctrl-Z, toggles between Undo and Redo. So, if you press Ctrl-Z repeatedly, all you get is Undoing and Redoing the same thing, which doesn't seem all that useful. In most programs, Undo just keeps undoing your work and Redo is mapped to another key.

Photoshop's Step Backward command, Alt-Ctrl-Z, is more like your typical Undo. They even have a counterpart, Step Forward, as Shift-Ctrl-Z.

That's all well and good, except for one super annoying quirk with Step Backward. It doesn't remember layer selection. Say you have Layer 1 and Layer 2. You do nothing on Layer 1, and then select Layer 2 and scribble a line. If you Step Backward, the line goes away and you're back on Layer 1. Why? Shouldn't switching layers count as a step? Heck, switching blending modes counts as a step, why wouldn't switching layers?