Had a window like that in the bedroom of our old Sunnybrook. The screen is on the inside and is held in by clips and has a big red handle on it so you can pull if off easily in an emergency. Un-clip the red lever, straighten it out, and push it outwards so the window will open like an awning window. You will find the lever has a detent half way along it so if will clip on the frame and allow the window to be held open as an awning style window. That's why it has a hinge at the top. For egress, push the lever handle all the way through and swing the window up so you can get out.
We used ours all the time, regretfully the new TT doesn't have that.
That window in the pic isn't frameless, I can see the screws attaching the frame to the RV below the blinds.