Does anyone know of a virtul keyboard that works with ANY software, specially with dosbox and scummvm?

The built-in virtual keyboard does not work. I also tried xvkbd, from open debian, but it runs as an applitacion, and not on top of other applications.

Or, does anyone know how to use the function keys in dosbox? That is, how to map some keys or some key combination to a function key?

Thanks a lot.