If gently but firmly pulling up on BOTH bottom corners at the SAME time does not work consider the following.
Normally when that window is unlatched it will, duh, fully open but if one or both of the gas charged lifts doesn't supply enough lift the window will pop open only about 1-1.5" which is not enough to clear the lift gate. That's what mine does and has done for quite some time. In my case the lifts have just enough "lift" left that I can then manually open the window (it will stay open in contrast to my hood which would not until I replaced the lifts) or in some cases if I pull on the gate latch it will open a slight bit more and let the gate clear.
With the window open 1-1.5" shine a light in at the lower corner. You will see the lower end(s) of the lift cylinder and the "ball" joint where it attaches to the window. Looking closely you will see a ca. 1/4" metal band on the end of the lift aligned with the middle of the "ball" joint. This is a spring "C" clamp that holds the "socket" on the end of the lift to the "ball" on the window. With careful use of a long flat blade screw driver or similar tool you should be able to pry the "C" clamp up (e.g. away from the "ball") enough to pop the ball and socket apart. For what it's worth you might try coming up from the bottom to get to the middle of the "C" clamp as there is usually a small notch there that lets you pry up the "C" clamp easily but I suspect you can accomplish the same thing if you come in from the edge and get the clamp partially pulled out and then work your way around.
See
http://www.amazon.com/Lift-Supports-C16 ... 081&sr=1-7 for a picture of the "socket" end.