title: Flex tree vertical scroll issue
body: <p>I have a flex tree control bound to an xml data from the database. I have item renderers for the tree items. My concern is, when my tree item size is huge, if I scroll using the mouse, it scrolls in 4-5 items at a time. I need it to scroll item by item. When it scrolls 4-5 items at a time, there seems to be a rendering issue as I have overriden lot of properties of treeitemrenderer and also the custom control i have put into the item renderer</p>
  
  <p>Is there any way I can change the scoll size?</p>
  
  <p>Thanks :)</p>