Comment 51 for bug 674138

Dave Gilbert : Indy is right
the f-f-m option sets the focus on the last window visited, and as long as windows are open the desktop never gets the focus. It means it is impossible to rename an icon on the desktop (or you need to open a file browser and open the desktop inside the file browser)
What I don't understand is that this issue would be solved with a very simple variant of focus-follows-mouse :
the behavior should be that
1- it focuses on the window under the mouse
2- it keeps the focus on the last window visited when the pointer is on the desktop
3- it focuses on the desktop if you click on it (and in general on any window you click in, since sometimes some bug makes the focus loose the mouse). In particular, when you click on an icon in the background (or create it) the focus should be automatically transferred to that icon...
currently the behavior is 1+2, but not 3.
to sum up, "focus follow mouse" should be a layer onto "click to focus", not an exclusive option.
this would still allow to visit the upper bar (for the crazy users who disable the menu-in-window feature).
The truth is that f-f-m is so handy that once one has tried it, it is hard to change back. (I first tried it on X-10... hmm, in '91?)