I’m modernising my house. At the back there will be a big picture window (grey frame) and the builder intended to put a traditional white sill below the frame, saying that it’s “normal” for the sills, architraves and skirting boards to match. I don’t think the sill will look right and wanted to just have the sill initially as bare plaster with a view to painting it later in a colour to be decided (either grey or to match the wall colour). He is scandalised! Is this such an unreasonable idea on my part? (The picture window is to “match” grey bifold doors on the other side of the room, so is the only window in the house which is grey on the inside).