Hello, Codeforces!!!
You've probably heard about keyboard shortcuts, and you've heard keyboard nuts talking about how they're so much faster than using a mouse. I think, it would be better if Codeforces will have shortcuts : )
For example, in CF rounds you would open problem A with shortcut Ctrl+Shift+A, to send your solution Ctrl+Shift+I and etc.
Well, it's not that hard to implement by yourself if you know js.
Though I don't really think this feature would be that useful anyway. You can open all problems on one page at the beginning of round, for example. Submissions by shortcut is fine but again it can only make things worse if you paste code instead of uploading file. All in all, I suppose that within browser people are used to mouse and it will take too many shortcuts to be convinient to use keyboard only.