How to modify Ext tooltips dynamically

I have a requirement to dynamically change tool-tips as content gets refreshed and modified. There were a couple of suggestions in the forums, but the following works great for me:

var mydom = Ext.get('mydomelement');       // get element
var tip = Ext.getCmp(mydom.dom.id + '_tip');  //get element's tooltip

if ( tip  )   {// tool tip already exists, so modify

   tip.title = 'new title';
   tip.html = 'new text';
}

else {   // tip does not exist.  Create it with unique id.

 new Ext.ToolTip({
     target: mydom.dom.id,
     id: mydom.dom.id + '_tip',
     title: 'title here', html: 'original text'
     });
}

I am giving every tooltip a unique id, based on the id of the dom element it decorates.