In the video above you can see two new features I have implemented: a fullscreen mode and dynamic sub menus.
The width of the menus now adjust to the width of the text of the options. When you click a menu item it will execute a callback function, this can either be another menu to open or something like FlxG.flash as demonstrated in the video.
The fullscreen mode is still a bit experimental and currently only works in a standalone Flashplayer. Please note that the bar at the bottom of the screen is still visible because the Camtasia screen-recording program is not very Flash-friendly. Due to security limitations Flash only allows applications to go fullscreen after a keyboard or mouse event, and I think Flixel might interfere with it because it takes care of the keyboard-handling for you.