I'm tiling the bathroom and on one wall the tiles only go halfway up. I'm
using that white trim to give a radiused edge to the top row of tiles. The
problem is where I go round the wall into the window. This is an external
corner so the trim needs to be chamfered at 45 degrees. The problem is the
vertical bit of trim which follows round from the window sill. It's a bit
like the corner of a cube where I have three edges coming together. It seems
to me its impossible to cut the trim so that all three bits fit together. I
think maybe all three bits should be cut square and a specially shaped
corner insert put in. I've never seen any inserts like this so I dont know
if they exist.

What is the correct way of finishing this corner?

Nodge