Hi there,
I have been working on the next version the last month, and there's some exciting progress. It's going to be a pretty big update and I still have a lot of work to do, but I thought I'd give you an update on some of the features and improvements you can expect.
The biggest thing is that I have changed the way drawing is implemented, to be able to support opacity, flow, transparent brushes etc. This was very tricky to get working with good performance and with live tile updating, but I think I have a solution that is general and works really well now. (in my tests it's even faster than the old system)

Improved onion skinning.

The 1px clean line function has returned.

Rearrangeable palette (still needs some work)

New canvas resize dialog

Some other changes:
- Improved selection rendering
- Per-frame animation delays
- Magic wand selection tool
- New flood fill implementation that works nicely with tiles
- Support for importing animated GIFs
- Support for importing BMPs
- Blend modes for layers
- Selection is kept after transforming
- Lots of UI tweaks
- Many other fixes and tweaks
The update should be available within a few weeks if all goes according to plan.