Mobile Client Session vs Desktop Client Session

I have a button with onMouseDwn (Custom Session property Room = 1) & onMouseUp Navigation to pgNext. This works perfectly in the Desktop Client browser. But only the Navigation (onMouseUp) is firing in the Mobile Client implementation. Both using same Pespective page. Any idea of what may be happening?

Use onActionPerformed on buttons. this works with mouseclicks and touch.
There also is an ontouch event i think, but then you would have duplicate code