It's not possible at the moment.
Also you can't change layout size. You can modify its scale though (as well as layers').
Scaling mode is the best bet, but relies on the size of the browser window and can't modify the original resolution (if your window is 1024X780 and your maximum screen resolution is 1920X1080 the maximised browser will take all the 1920X1080 pixels but scale a 1024X780 "image" to fit this space).
Also since r73 sclaing appears to be buggy a bit (it will surely be fixed in a future release).