When you press Alt-Tab, you get the nice popup with icons representing each
window. Sometimes, when you have lots of windows open, you can see the icon
representing the window you want, but to get to it you have to cycle through
quite a number of other icons (by pressing Tab lots of time). It would be nice
if you could use the mouse to click on one of the icons in the popup. The
selection (highlight) would then move to that icon (meanwhile Alt is still being
held down), saving you an awful lot of Tab-pressing. The actual selection of the
window and termination of the popup would then happen in the normal way when you
release Alt.