Pretty much all of the Cessna singles use a similar mechanism for the window support arm and, if the support is disconnected, aerodynamic loads will hold the window fully open.
Something to note when disconnecting the support arm: There's a spring mechanism that attaches to one end of the support arm. Can't remember if it's inside the window frame or inside the door.
Whichever location it is, you're better off disconnecting the other end of the support arm ie the end that pivots around a screw and the not the end that connects to the spring. Use some sticky tape to restrain the now free swinging arm.
If you remove the screw from the spring end the spring retracts/falls back into the frame & is a pain to re-attach.