When I tap on either side of the screen, it will bring up the virtual keyboard.

How can I make it so that this only happens just once?

A double tap by accident will stack two of them on top of each other, still leaving one of them on the screen after the other one closes.

This is the script I'm using to launch it.

xkbd -geometry +65509+140 -k /media/mmc2/N800/Keyboards/scumm.xkbd & echo $! >/tmp/xkbd2.pid

Cheers.