This happened to me also. What I did was glue the tabs back togeather with super glue. While using a clamp to apply pressure, I super glued the tab back to the window. For extra support, I fabricated a aluminum tab that would go over the plastic one and would be glued to the window. Worked fine for me

I tried using epoxy for this before ( I think it was called JB weld, "Worlds strongest Epoxy"), but due to window binding, the tab just broke in half and epoxy was not holding it anymore.