seOut="HideTip('tt27')">mxEvent.BEGIN_UPDATE</a> or <a href="../util/mxEvent-js.html#mxEvent.END_UPDATE" class=LVariable id=link54 onMouseOver="ShowTip(event, 'tt28', 'link54')" onMouseOut="HideTip('tt28')">mxEvent.END_UPDATE</a> for the bottom up and top down phases after changes to the graph model.&nbsp; <a href="#mxLayoutManager.mxEvent.LAYOUT_CELLS" class=LEvent id=link55 onMouseOver="ShowTip(event, 'tt31', 'link55')" onMouseOut="HideTip('tt31')">mxEvent.LAYOUT_CELLS</a> is used to check if a layout exi