He said it's in the USA version of OXM.
Like I said on gtaforums:
Wasn't it possible to jump from rooftop to rooftop in San Andreas? Many tags were hidden on roofs, for example, and so were weapons. One of the most memorable examples was Grove St. where you could climb up a house and jump from house to house until you reached a tech-9.
Someone posted this at gtaforums:
I belive you but if you want the rest of the world to do so show some proofs.About the car trunks this feature was supposed to be in GTASA but was removed for unknown reasons.About the roof thingy i just hope it isnt something Spiderman/Superman way...
Edit:this is what i mean