OrangeTapioca There is no menu. F4 does nothing but quit/close the game entirely - Quick exit. The menu will be under the pause screen when it's implemented. Right now it's just the stats screen.
The only event attached to pressing f4 is:
<img src="http://designchris.com/ibbeta/dondoit.png" border="0">
And it appears to be an open issue with node-webkit:
link to NW error for C2
So it's just a node-webkit app quit issue for windows 8. We have to wait that one out.