I got tired of the window slamming shut, so I slightly over-engineered this solution. It automatically latches on the handle, if positioned correctly, and releases again by pushing the button on the underside. 

Assembly

The main body can be screwed into place with 2 countersunk screws, 3.5mm diameter. 4mm should also work. Don't overtighten, otherwise the print will crack (but probably still work). The other small green part in the image is the pin that holds the latch in place. The button can be placed before or after assembling the latch, should work either way.

How to print

All parts can be printed without supports, though I recommend some mouse ears brim on the pin. The pin might be slightly tight in the hole of the body, but should fit without much coercion. 

I printed all parts in PLA, 0.4 nozzle, 0.2 layer height, 3 walls, 12% gyroid infill.

Happy printing!