I had that exact situation in a bath remodel we just completed - 60" tub/shower combo with a window smack dab in the middle. The window itself was a fairly new vinyl window, but the trim, sill, etc. was wood.

We used onyx to redo the bath - panels for the tub walls, vanity top/sink, and window trim. It was quite easy for my contractor to cut the 60" panel around the window. Well, I suppose that's easy for me to say. :0) And all window trim, including the sill, is now onyx. Looks quite nice and is completely waterproof.

No, I don't work for this company.

Here is a link that might be useful: Onyx

Thanks for the link. What does the 3 panels cost if you don't mind me asking?

Well, I'm not sure of the exact cost, because I bought it thru my son's discount. He works at a lumberyard/home store. About time I got some benefit from him, rather than vice versa! :)

I bought 3 panels plus top trim for the panels, all window trim, and a 36" vanity top/sink for about $1,800. But as I said, this was with my son's discount, and I'm not sure what percentage that was. At least 25% off, I'd say.

Oops, I forgot. I also got an 18" shelf and a corner shelf in that price, too. So I would guess that the panels were about 1/2 of my total cost.