Hi Barry,
Yes, If I change the material of the sill, it does change. I double checked, and the "real" windows in the exterior walls do not have sills or casing. The window that I am using in the cladding, which shows the sill and casing, is the "Rectangular Window Opening 19" from the R19 library. I should also note that when I render the model, it looks fine, which is why I don't want to just change the casing material to something that shows as white. If I change the material to something else, it does change the casing in elevation. For example, if I change the casing to "Aluminum" the black infill goes away. I could, I suppose, keep the material that I want when I publish the renderings and change it every time I want to print the elevations, but that promises to be a major pain in the neck. For the life of me, though, I cannot figure out why the same material would be shown differently in two different parts of the same window. This is consistent throughout the entire model, by the way, not just one or a few windows.