If your newly created window for Sims 3 has either white or opaque glass, there are a couple of reasons why this could be. Here’s how to fix the issue.
If you changed any of the shaders for your glass, ensure they are set to Glass For Portals only. The materials used by your glass are listed on the MESH tab of TSR Worskhop 2.0 as shown in the image below.
If you didn’t touch the shaders, then the most likely cause of this is that you made your own glass.
For some reason, meshing your own glass does not work well with some windows, and it is therefore better to use the glass in EA’s original Sims 3 object and reshape that to fit your window. This will cure the problem.