I use Linux, specifically Mint 13 with cinnamon. However, I'll be happy with answers that apply to a more recent version of Mint, or a current version of Ubuntu or one of its offshoots.
I often have a number of applications running. I can scroll a window by moving my mouse cursor over top of it and using my scroll wheel. However, this does not change focus to that window. Is there a way to force this to happen? That is, I would rather not have to click on the window, I expect just by scrolling, the window should gain focus.