Eraser Transparency

The soft edge option on the eraser is great, but a transparency option, I would say, is an absolute MUST for an animation app.

You really need to be able to sketch and then take back (partially erase) a drawing before sketching over and finessing the lines. Often, the sketching and taking back can go on for several iterations before a drawing is ready.

Currently this can be done by using the onion skin feature and moving back and forth between two frames, but being able to take back a drawing with a 50% transparent soft eraser would be so much better.