How to deselct drum voices in the drum palette

Hi,

Is there a way to deselect drum voices in the palette so that no voice is selected?
It seems that once a voice is selected you cannot clear. This causes a problem because a MIDI keyboard (and the onscreen keyboard) regardless of which key you press will always input what the drum palette is set to, rather than the map across the keys. It also means that the repitch function stops working from the MIDI keyboards. The MIDI keyboard input works fine as long as you don't touch the drum palette first.
I cannot find a way to clear the palette apart from closing down the program.
thanks