code: func dragGrab(xu *xgbutil.XUtil, grabwin xproto.Window, win xproto.Window,
  	cursor xproto.Cursor) bool {
  
  	status, err := GrabPointer(xu, grabwin, xu.RootWin(), cursor)
  	if err != nil {
  		xgbutil.Logger.Printf("Mouse dragging was unsuccessful because: %v",
  			err)
  		return false
  	}
  	if !status {
  		xgbutil.Logger.Println("Mouse dragging was unsuccessful because " +
  			"we could not establish a pointer grab.")
  		return false
  	}
  
  	mouseDragSet(xu, true)
  	return true
  }
docs: // dragGrab is a shortcut for grabbing the pointer for a drag.