303 both the cleaner and protectant is good to use on the canvas. I use a product from IMAR, their products are designd to be used on Isinglass and clear window vinyl.
Both products mentioned above are excellent. I have used the 303 protectant since getting my hawk, usually twice a year. 2005 model and fabric is still pliable with no cracking. What ever you choose, be sure it doesn't contain petroleum as an ingredient, 303 does not.
my atc maintenance procedures page says to use 'warm water and a soft cloth' on the clear plastic windows.
they also say 303 is good for the vinyl pop up liner, inside and out.
Used 303 on tanou cover on truck before 4WC and was great cleaner and preservative for that. Then used on all of vinal on camper including windows with no problem. Is a good product.
For some reason I remember hearing not to use anything but water and maybe a mild dish soap. Apparently no on Windex, and I have never used 303 on the clear window, only on the soft side, so can't say yes or no. Use a soft cloth so the window doesn't get scratched.