WD40 should not harm the glass or the defrost lines. WD-40 is the go-to product for silencing squeaks, displacing moisture, preventing rust, and loosening stuck parts. You probably have a can sitting in your garage right now. It has a ton of uses, but it’s no panacea. WD-40 will not harm your car’s paint and should work to remove sap, tar, adhesives and even chewing gum from seats and carpets. Just spray, let it sit for like 5 minutes and wipe clean with a microfiber towel. Afterwards you should wash the area with soap and water and reapply wax since WD-40 will strip it.
However, the best way to remove tint glue is 0000 wire wool and a mixture of hot water, dawn and ammonia. Zippo lighter fluid works great along with some 0000 steel wool. Refer to this page for more ways. If you’re ever in a hurry and don’t have the above listed items available,
you can always use vegetable oil (Wesson, etc). You can skeet a 50/50 mix of water and liquid fabric softener on there, too. That works well.