First of all great idea for software! Just love it :)
I have few ideas: (I have more, but let's start some where)
- Toggle shortcut-keys for background/image visibility is sheet window.
For example: Button 1 goes down. Current state is saved and Background is made opaque. When button is released, it restores the state.
This would be much better than back-n-forth slider. And much faster to use.
- Mouse Wheel for Zoom and/or Brush Size
For example: Mouse wheel sizes the Brush and Mouse wheel + Ctrl key is Zoom for the Sheet, rather than sizing the window it self.
- Label some where which tell what frame you are and total frames count.
- Shortcut-keys for:
- Add Frame ( For example: Ctrl+F -> for to last, Alt+F -> After this frame )
- Next / Previous Frame
I noticed that the software captures some of the keyboard keys while it is running. For example I can't type all my letters and space while the software is running. I have to exit to get them back working.
But as i said, I love this. I hope you keep developing this!