I think I've written about this before, in one of my games it was my turn and I was seeing a granade behind a door. This granade was not in my field of vision. I think that was an advantage for me just because I knew there were enemy units over there. Same happens with opened doors, and I remember Steve told me it was ok this way, but again I'm not sure about that. It just helps opponent because your position gets revealed, or am I missing something?? M
It's the way the original game did it. It's not very realistic, but it does add an extra dimension to the strategy. In the original, you could "hide" grenades by dropping them on the same square as a plant or something.