One of the commenters points this out, but bringing the under-the-mouse application into focus isn't strictly speaking a problem, assuming it doesn't fuck up th

One of the commenters points this out, but bringing the under-the-mouse application into focus isn't strictly speaking a problem, assuming it doesn't fuck up the window stacking (although it might be a little slow). An approach that might work would be to bring the application under the mouse to the logical "front" (i.e. it's menu bar shows up), but suppress the re-ordering of windows that normally occurs. This would probably be an OS-level thing that Apple would have to do, however, rather than something SteveY could hack together in two days. FFM does work within any one application, since Terminal supports it: defaults write com.apple.Terminal FocusFollowsMouse -string YES (you have to re-launch Terminal). Then all Terminal windows do FFM, and the focused window has the standard focused appearance, except without popping to the top of the window stack like it normally would.