Hi there,
Every time I've tried to set that Extended Window Style property once I've created a RenderWindow (Style::None) it returns me an error and the property wasn't applied.
Finally to make it work, I had to change the source code in WindowImplWin32.cpp.
What I did was just to add another DWORD variable dwExStyle set to this property and to change the macro CreateWindowW and CreateWindowA since they didn't take any extended window style into account.
Is it normal? I've tested the same code with another hwnd I create manually and it works fine.
What makes it fail here then with Sfml?
Cheers!