jmclean/datagrid/src/TooMuchValidation.mxml

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
			   xmlns:s="library://ns.adobe.com/flex/spark" 
			   xmlns:mx="library://ns.adobe.com/flex/mx">
	<s:layout>
		<s:VerticalLayout />
	</s:layout>
	
	<fx:Script>
		<![CDATA[
			import mx.collections.ArrayCollection;
			import mx.controls.dataGridClasses.DataGridColumn;
			import mx.events.AdvancedDataGridEvent;
			
			[Bindable] public var rowcols:ArrayCollection = new ArrayCollection([
				{col0:0, col1:0, col2:0, col3:0, col4:0},
				{col0:0, col1:0, col2:0, col3:0, col4:0},
				{col0:0, col1:0, col2:0, col3:0, col4:0},
				{col0:0, col1:0, col2:0, col3:0, col4:0}
			]);		
			
			/* 
			* To reproduce  bug
			* 1. Roll over cells watch count go up
			* ISSUE only changed cells only need to be validated and only once!
			*/
			
			protected function showCalled(item:Object, column:DataGridColumn):String {
				return String(item.called);
			}
			
		]]>
	</fx:Script>
	
	<mx:AdvancedDataGrid id="datagrid" dataProvider="{rowcols}" selectable="true" itemRenderer="ItemRenderer" />
</s:Application>