Some chams that feel too confined or too exposed may try to reach the more desirable trees and bushes they can see from the window. It may be a very individual thing based on whether they are (for example) a wc adult, a very active species, and how secluded or roomy their indoor territory is. I had one of 3 free range melleri that always paced and pawed at a window. The other 2 didn't once they were settled into their space.