I'll start of by saying that I love this software. It's very nice and modern and better than Paint.NET for spriting. I have a few feature requests that I feel would make the software much more convenient to work with. They are small features, but extremely useful nonetheless.
Zooming way out and way back in gets me lost. Can you center the canvas when the user is zoomed out enough such that the canvas fits in the gray area behind it? (Kind of like Paint.NET). If I zoom far out and try to zoom back in, it's kind of annoying to have to put the mouse on the canvas in order to zoom into the picture.
I also saw a drop down for the right mouse button. There is a color picker option and a 2nd color option. Can you add an eraser option? I know the erasing can be done using the color picker and picking an empty pixel, but I think it would make my workflow more efficient if I could erase with the right button when I'm drawing outlines.
Another cool feature that I've never seen before, but I always wanted to see in a paint program was the ability to hotkey palette colors. By pressing CTRL+(any number from 1 through 0 on the keyboard), the user will save the color in a hotkey and he/she can recall it by pressing any number from 1 through zero. This is kind of how Starcraft 2 does hotkeys. Furthermore, when a hotkey is assigned, markers at the bottom of the screen should show what color is assigned to what hotkey. See this image for reference: http://www.sc2sea.com/images/guide/zerg/zmech1.png
Also, it would be nice if all the hotkeys were reachable by the left hand on the keyboard when the index finger is resting on the F key. For example, the letter D could be used to delete the selection. Additionally, since people are already used to pressing the Delete button, you could just make both keys call the delete function when either is pressed.
Finally, it would be nice to have effects like Hue/Saturation adjustment. This would make it easier to make multiple versions of a sprite with different colors.
Thanks for the software, and I look forward to continually supporting it!