Set the highlighted background color of win to bg. This color is used when win has the focus to draw most of the window decorations, along with the relief colors generated from it, which are used to draw the window's 3-D bevels. win defaults to the window context in the usual way if not specified. If bg is #f, then lets the decor highlight background color be used (turns off a special highlight color for win). See also get-window-highlight-colors.