A graphics context can be used for drawing on any drawable that is on the same screen and that has the same depth as the drawable for which it was created. This means that a GC created for a window on a 256-color screen can be used for any window or 256-color pixmap on the same screen, but it cannot be used for drawing on a pixmap of depth 1. In this case, a separate GC must be created for the 1-bit pixmap.