Another feature i was thinking about dunno if it could be added in, and might be nice would being able to control a rotation of the sky box and possible dual layred sky boxes.
For instance if you wanted to make a space game and when from building to building outside on a planet such as mars it would be nice to have dual layers one with stars planets and such, and one with clouds where the stars/planets where stationary and the cloud box with a alpha trans set to 50 (half visible) would rotate the clouds slowly. Or stars on one box and a alpha 50 with stars on another rotating very slowly giving more of a depth type look to the sky.
It can be done in dbp obviously and it usually looks nice, thought it might be able to be added into fpscreator if enough people would be using it.