Okay, I have new pause button/next button code out just now. The pause button should no longer break if you use the "next" button while paused.
In addition, the next button now works in the following way in class mode: If you are more than halfway through the time you've been allotted to draw an image and use the "next" button, the tools will assume you've finished early and move you to the next pose in the class. But, if you're LESS than halfway through the image's time, it will assume you just didn't care for the image you were assigned for that segment and change JUST the image, without advancing the class segment. Hopefully this is a better balancing of competing concerns and makes more people happy. :)
I've also slipped a test version of the code that's meant to stop mobile devices from going to sleep while you're drawing into that patch.