How to get an arpeggio over full grand staff

You can extend an arpeggio to notes in another staff of a grand staff that are in the same voice by putting the arpeggio into edit mode (double click it or use the shortcut which I changed for my system), click the grab box that will extend it in the correct direction and press ctrl+shift+ arrow (like cross-staff notation). One feature about this is that you can extend the arpeggio to as many staves as you like. I'm working on a score that had the arpeggio span 3 piano staves and discovered it extended once per ctrl+shift+arrow.

The secret to making your score look right is to swap voices in one of the staves so voice 2 is on top and voice 1 is on bottom. You can then adjust stems if needed so the top notes are stem up and bottom notes are stem down. It should be as simple as selecting the entire measure on that staff and pressing x. Doing this before you extend the arpeggio will make it look right. It still doesn't support proper playback.