You're too fast for me. You beat my edit again. I was going to add, "in front of you" may be ambiguous. I was thinking of it as which window? The window in front of you.
But in the original sentence, "I opened the window in front of you, haven't you seen?" - "in front of you" could be the fixed idiom (I think) meaning "I did it while you were addressing me." In other words, I had your attention. (I guess I'm using "addressing" as when a golfer says, "I'm addressing the ball.") If this is the meaning of "in front of you," then your call for past tense may be correct.