1)I think Alt+S doesn’t work with proportional editing. Why is that?
2)Pressing J to see the previous rendered picture gets me a black image. It does have to be pressed in the render window, right?
- Pressing J. Press F12 to render F11 to show previous render. Pressing J in the render window stores in a buffer your render (the first time) then if you change something and F12 render. Then after the render hit J shows previous stored buffer image. continueing to press J flips back and forth with the buffer. Used to compare changes.
Paradox
you do it this way:
render first time
press j [will turn black]
render again
press j to see previous render
the last buffer that was opened when you render is the one that is rendered over
Thanks! 
But what about Alt+S? I use it as a grab tool, when vertices aren’t aligned exactly along an axis. But I use proportional editing too, and they don’t seem to work together.
Egg: Yes, that’s right. alt-s doesn’t work with PET, someone was too stupid to implement it. Live with it 