code: func (w *Window) Stack(mode byte) {
  	xproto.ConfigureWindow(w.X.Conn(), w.Id,
  		xproto.ConfigWindowStackMode, []uint32{uint32(mode)})
  }
docs: // Stack issues a configure request to change the stack mode of Window.
  // If you're using a window manager that supports EWMH, you may want to try
  // and use ewmh.RestackWindow instead. Although this should still work.
  // 'mode' values can be found as constants in xgb/xproto with the prefix
  // StackMode.
  // A value of xproto.StackModeAbove will put the window to the top of the stack,
  // while a value of xproto.StackMoveBelow will put the window to the
  // bottom of the stack.
  // Remember that stacking is at the discretion of the window manager, and
  // therefore may not always work as one would expect.