(I don\'t want to hear about how crazy I am to want that! :)
Focus-follows-mouse is also known as point-to-focus, pointer focus, and (in some implementations) sloppy
The menu issue is the only reason traditional focus-follows-mouse wouldn't work.
Here's an alternative: don't change focus until a key is pressed on the keyboard. This would cover 95% of use cases for focus-follows-mouse, and would make this old curmudgeonly X user really happy. I don't know how many times I'll be scrolling through a web page in Chrome, and hit Command-T to open a new tab, and find the tab opening in the Terminal instead. If my brain hasn't picked up on this in 8 months of using a Mac, it never will.