On Saturday, 17 August 2019 21:04:30 UTC+1, ss wrote:
I would have thought however to silicone just the internal side and not
the external side of the screen as that would prevent any water getting
under the glass screen.

Am I missing something?

The way I think of it is that the silicone seal *will* definitely fail at some time. It might take a year, or it might take ten. But when it fails, water *will* end up in the frame and/or around the screen.

So, given that water *will* be there, it's better that it can freely drain out into the shower tray, rather than onto the floor outside of the tray.

So seal the outside.