  *  <p>Transitions in DataGrid item renderers aren't supported. The GridItemRenderer class 
  *  has disabled its <code>transitions</code> property so setting it will have no effect.</p>
  * 
- *  <h2>Efficiency Considerations</h2>
+ *  <p><b>Efficiency Considerations</b></p>
  *  
  *  <p>DataGrid scrolling and startup performance are directly linked
  *  to item renderer complexity and the number of item renderers that

        else if (dataTip && !showDataTips)
            toolTipClient.toolTip = null;
    }
	
	/**
	 *  Shows the tooltip for one of the grid's item renderers.
	 *  This is the handler for the <code>ToolTipEvent.TOOL_TIP_SHOW</code>
	 *  event in GridItemRenderer, DefaultGridItemRenderer, and 
	 *  UITextFieldGridItemRenderer which are installed by the corresponding
	 *  constructors.
	 *  The item renderer's tool tip is computed just before it is shown.
	 * 
	 *  If the item renderer's column <code>showDataTips<code> property is true, 
	 *  a placeholder tool tip is registered with the tool tip manager so that 
	 *  mouse handlers are put in place to detect when the tool tip should be
	 *  shown by calling this handler.
	 *   
	 *  This handler replaces the placeholder text with the actual text and 
	 *  resizes the tooltip before moving it into position.  
	 *  The tip is positioned over the item renderer with the origin of the tip 
	 *  at 0, 0, after accounting for the layoutDirection of the grid.
	 *  
	 *  The current target is expected to implement IGridItemRenderer and
	 *  IUIComponent.
	 */	
	static mx_internal function toolTipShowHandler(event:ToolTipEvent):void
	{
		var toolTip:IToolTip = event.toolTip;
		
		const renderer:IGridItemRenderer = event.currentTarget as IGridItemRenderer;
		if (!renderer)
			return;
		
		const uiComp:IUIComponent = event.currentTarget as IUIComponent;
		if (!uiComp)
			return;
        
        // If the renderer is partially obscured because the Grid has been 
        // scrolled, we'll put the tooltip in the center of the exposed portion

        if ((rendererR.height == 0) || (rendererR.width == 0))
            return;
            
        // Determine if the toolTip needs to be adjusted for RTL layout.
        const mirror:Boolean = renderer.layoutDirection == LayoutDirection.RTL;
        
        // Lazily compute the tooltip text and recalculate its width.
        toolTip.text = renderer.column.itemToDataTip(renderer.data);
        ToolTipManager.sizeTip(toolTip);
        
        // We need to position the tooltip at same x coordinate, 
        // center vertically and make sure it doesn't overlap the screen.
        // Call the helper function to handle this for us.
