@DOWA Thanks for this nugget of information! This is never mentioned in any presentations or discussions that I have seen.

I should also add. When changing a window to a different opening arrangment / type, all the previously defined properties of the opening are lost which is time consuming to rectify.

Reveals are a general bugbear of mine. I don't like not being able to correctly show reveals with a different makeup from the main wall construction, ie. insulated plasterboards.