Hey daffy... I had new pvc windows fitted during the summer and tried the adhesive hooks and rods... unfortunately, the weight of my nets (cotton, not voile or polyester) was too much for them and they kept falling off ... Everyone suggested superglue but I didn't want to do anything permanent like that !
In the end I managed to find some adhesive velcro hook tape that I could fix to the top of the window (and it's easily removed if necessary, with no residue left)... I then sewed some *drape and tape* curtain header tape to the top of the nets, gathered them up like normal curtains and simply pressed the header tape to the velcro hook ... voil� ... my nets are securely fixed to the windows but easily removed when I need to launder them etc. I couldn't believe that this special header tape would actually fix to the velcro but it did !