We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Mike Lane
saying something like:

Not really a diy question (and may be silly) but...

I'm thinking of having double glazing fitted in my bathroom, and I'm
wondering about an extractor fan that I have mounted in one of the window
panes. It really is in the best position as it is, and it would be difficult
to move it anywhere else.

Is there any way I can mount the fan in a double glazed unit?

The supplier can do that.
http://myreader.co.uk/msg/1391146038.aspx