Whenever I compile my map, it returns an error that says [COLOR=Red]MAP LEAKED[/COLOR] and there is a red line going from my info_player_start to my func_glass entity where it turns and continues outside the map like this:
I didn't make it!
The func glass cannot look out in the grey zone. It needs something behind it like a sky texture.
It's not just glass, all types of entities cannot touch the void.
If you're making a house with many window's looking out, then I suggest following Juggernut's advise and put a skybox around you're map. ( or simply just around the windows)
Only structural brushes can touch the void.