1) press "mode" key shortly for enter/exit <alt mode>, press "mode" key longer for original function
2) press playback (>) key in CHDK menus as disp/erase button
3) press "menu" key during video recording for Ev correction

Known bug:
UI bitmap palette does not work correctly. http://chdk.setepontos.com/index.php?topic=11831.msg117245#msg117245