This is a difficult question. Even for someone who knows what they are talking about. It all depends on legal requirements, building materials, construction, general humidity etc. But getting an expert opinion is a very good idea - not to say necessary. Leaking / mould is a nightmare and you may run into insurance problems.
That said, I have seen windows in showers similar to what you describe. In fact, there was one in our house many years ago. We ended up moving the shower and had to change the window and the construction around it because of moisture. Pretty sad sight when the window was taken out.
Redoing another bathroom now, we discussed a similar possibility, but decided against having the shower near the window. IF we had opted for the window in the shower shower, the proposal we discussed was to seal the opening using a glass brick window similar to the image below with a shower in the corner (with the window smaller and higher up). But then, we ended up having the shower in another corner.
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(from SF 3D models 370)
