I use this product.
303 Products, Inc.: 303 Aerospace Protectant
You can often find it at places that sell marine supplies.
If, after long storage, I have a window sticking to its gasket despite use of this product, I
pull the widow open with a suction cup. The type that has a vacuum release. I think it is safer than trying to pry the glass open - although I initially did that using popsicle sticks! I'm afraid prying might break the window, although I'm sure it is tempered glass.
I have Fantastic fans with power openers. Quite often the first time I want to use them, they stick and cannot be opened by the motor. In that case I just help the motor along a bit by applying a light pressure to the manual opener knob at the same time the motor is turning it.
Occasionally it still doesn't want to open, so then I reverse the motor to close the lid down tight, t hen try to open again - so far, that has always worked on one try!