Tryin' Out Open Canvas

So I find out that Open Canvas can finally be used on Vista. About bloody time. Now I can find out why some of my fellow Deviants think it's the Dogs Bollocks (TM).

Since I haven't used my Graphire 4 in a while, I figured I just do a few exercises before trying to do a actual picture. I have to admit though, it is pretty impressive so far. And before you say anything, Yes I know I messed up on the cube.

I do have a question though: How can you fine tune the erasers, cause I keep getting like an airbrush effect every time I use them....