1. Revert - a simple and fast way to go back to a saved version.
2. Close - menue item that enable me close my open drawing.
3. Let me choose between pixels, cm, inch, mm (etc) when I want to change my drawing size.
4. Using any tool, I need an option of "adding" or "subtracting" hue or color to my drawing. this is a realy advantage of using the computer as my drawing tool vs the real canvas. Instead of re-drawing a certain part where I want to put some shadow (for example), I would take this tool (or option) and choose "darker" and apply it on this area.