screen io nn
where nn determines if color is used when displaying the application window (BACKSCREEN) and any user-generated Zim windows. For values 1 and 2, color is used if the display device supports color. For values 3 and 4, the Windows control panel colors are used. Values 3 and 4 are often useful for VGA monochrome screens where color is displayed as different shades of gray (which can be difficult to read). For values 5 and 6, color is always used even if the display does not support it.
nn = numeric entry 1 to 6