Also, not sure if it's a bug, but throwing a grenade at the windows I've shown in the third screenshot doesn't break them like one would think they would. Also, the third screenshot is another window that grenades seemingly can't go through, like in the original bug I reported.
Window 1: http://imgur.com/LnvHeKG
Window 2: http://imgur.com/yei9X5S
Window that can't be broken by grenades: http://imgur.com/eMxgmPt