code: func (im *Image) XPaint(wid xproto.Window) {
  	// We clear the whole window here because sometimes we rely on the tiling
  	// of a background pixmap. If anyone knows if this is a significant
  	// performance problem, please let me know. (It seems like the whole area
  	// of the window is cleared when it is resized anyway.)
  	xproto.ClearArea(im.X.Conn(), false, wid, 0, 0, 0, 0)
  }
docs: // XPaint will write the contents of the pixmap to a window.
  // Note that painting will do nothing if XDraw hasn't been called.
  // XPaint is what switches the buffer (drawn to using XDraw) into the window
  // to be visible. That is, multiple calls to XDraw can be made, and the screen
  // will only be updated once with a call to XPaint.