In reply to Sam Jacobs
"They're a software implementation of a hardware device that is generally, under traditional desktop conventions, expected to always be present."
I second that as I use onboard on WVGA touchscreen only device without hardware keyboard. It is essential that it's always present.
In my opinion the best solution will be to add the big hide button https://bugs.edge.launchpad.net/onboard/+bug/564040 . As I commented in that bug, with such hide button one could start onboard without window decoration. This would save display space (essential on 800x480 device) and remove the danger to unintentionally close onboard.
The auto show/hide feature would as well be an enormous improvement for small screen device: https://bugs.edge.launchpad.net/onboard/+bug/443986