For tinting windows, I use Future and food coloring.
1. Coat the entire windshield with Future (I usually just dip it into a vat of the stuff, set it on paper towels and blot the excess that pools near the edges with a paper towel)and let dry overnight.
2. Repeat step 1.
3. Mix the desired color of tint using food coloring, more color is desired as the Future will be applied in a thin coat.
4. Quickly Dip the desired portion of the windscreen in the tinted Future, blot at the edges and let dry overnight. DO NOT TRY TO GET IT DARK IN ONE COAT as the Future is very thin and will dissolve itself if not allowed to dry.
5. repeat step 4
6. to remove any drips or slight errors, use a qtip in clear Future and rub the color away.
I have used this technique to great success, check out the bubble top attached...it is green with a clear front area.