I'm using FFM in Ubuntu classic (non-Unity) right now. Mouse and keyboard events go to the highlighted window and the highlight follows the mouse (with a few minor exceptions which is why some people call it sloppy focus). Clicking doesn't affect where the events go.
Not sure what you're talking about...? Maybe plain old click-to-raise like Mac and Windows?
I'm using default Ubuntu classic behaviour currently, and I almost agree with windsurfer's description. (I'm currently using 11.04, dist-upgraded from a 10.10 clean install, but it's been this way in every Ubuntu I've used over the past four years.)
If I mouse to a different window, focus does not follow (like MS). However... if I use the mousewheel, it applies to whatever window is under the mouse. As windsurfer says, this is cool because I can navigate around in one window while keeping my editor typing in another.
However, in disagreement with windsurfer's claim, my middle-click DOES change focus, as with my left- or right-click.
Anyway, I hate full-on sloppy focus, but I sure love this sloppy-mousewheel-focus.
Not sure what you're talking about...? Maybe plain old click-to-raise like Mac and Windows?