Lobster wrote:

(And I've never fitted a window with the glass already in place - would
hate to have to do that, for the weight, fragility and unwieldiness.)

David

The ready made windows from B&Q or Wicks (can't remember which... maybe
both) come with some rather dodgy looking plastic tabs to clip on the
frame and screw on to opening leaving the glass in place during
install. It doesn't look like it would be a lot of fun fitting one of
those.