The function paints a rectangular area in the specified window according to the specified dimensions with the window's background pixel or pixmap. The subwindow-mode effectively is If width is zero, it is replaced with the current width of the window minus x. If height is zero, it is replaced with the current height of the window minus y. If the window has a defined background tile, the rectangle clipped by any children is filled with this tile. If the window has background the contents of the window are not changed. In either case, if exposures is one or more events are generated for regions of the rectangle that are either visible or are being retained in a backing store. If you specify a window whose class is a error results.
can generate and errors.
The function clears the entire area in the specified window and is equivalent to (display, w, 0, 0, 0, 0, If the window has a defined background tile, the rectangle is tiled with a plane-mask of all ones and function. If the window has background the contents of the window are not changed. If you specify a window whose class is a error results.
can generate and errors.