When the hardware keyboard is open, whats the purpose of an onscreen keyboard?

When the hardware keyboard is closed, how do you open the finger keyboard? You can't, it requires pressing the rocker button which is on the hardware keyboard (??!)

It seems a basic UI design idiocy to me. Wouldnt you agree? There should be a way to set the tablet to use the thumb board _only_ (no stylus typing for me), and to only open when the hardware keyboard is shut. As it seems this cannot be done, I thought I would assign it to one of the other hardware keys perhaps through a shell script or mce.ini or something.

Thanks all for your responses.