Regardless of what anyone tells you, you CAN'T drill tempered glass.
You will end up with a basket full of pieces a little bigger than a pencil
eraser.

All of that kind of work is done BEFORE it is tempered.

Once you get through the layer that is under surface compression,
the residual tension in the core of the glass propagates crax like
crazy.

So if you get a window that needs a latch glued on, you just have
to glue it on. No guarantees.
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma