I want to be able to switch between windows listed in my taskbar just by hitting F1-F12. The idea is that the entries in the taskbar should begin with a number between brackets, i.e.:

[1]Firefox [2]Dolphin [3]KTorrent, etc. I can't find a way to do that.
There is an option to assign a 2-key shortcut to a specific window, but the shortcut is lost when the window is closed.