If you press E while standing next to a broken window your character will start trying to force it opened. If you just leave them to do it they'll always get it eventually. Always. It's just a matter of time. So you don't actually have to break them. Unless of course it's like a floor to ceiling window or store front window that can't be opened without being broken. I never knew that! I always break a window if the doors/windows were locked; ill give this a try next time i'n on Cheers guys.
Im struggling to hand a sheet rope from the upper of the Sunstar hotel; all the windows are locked, and when i smash them, the option to hang one is not there. I have a sheet rope and a nail in my inventory.