Turn on cycles go to the color picker, change the color, then allow cycles to render for awhile with the new color. Press escape to exit the color picker and cycles begins rendering from the beginning instead of continuing the existing render that started when you last picked the new color.
Another thing with this theme:
continuously repeating "restart Cycles render" on Grab operation.
- default scene, enough passes in Preview to be noticed (100 maybe)
"rendered" in 3dView,
- press "G" (cube is selected)
- move Cube a bit
- don't complete Grab, just release your hand from the mouse...
I get 3 passes and after this Cycles restarts rendering. Not a big bug but when you're trying to use it wisely and like a "preview machine with interactivity" - it fails.
Excess actions like end of Grab (rotate, scale... another operations) spoils interactivity.
Fixed the color issue, actually the bug was that escape would not reset to the original color as it does for other buttons. I can't redo the grab issue though. It also seems like a completely different bug, so it doesn't really belong in this report...