      *  this property specifies the actual height of each row, in pixels.
      * 
      *  <p>If <code>variableRowHeight</code> is <code>true</code>, 
-     *  the default, the value of this property is used as the estimated
+     *  the value of this property is used as the estimated
      *  height for rows that haven't been scrolled into view yet, rather
      *  than the preferred height of renderers configured with the <code>typicalItem</code>.
      *  Similarly, when the Grid pads its display with empty rows, this property

    
    /**
     *  Return the data provider indices and padding indices of the 
	 *  currently visible rows.  
	 *  Indices which are greater than or equal to the 
	 *  <code>dataProvider</code> length represent padding rows.
     *  Note that the item renderers for the first and last rows 
     *  may only be partially visible. 
     *  The returned vector's contents are in the order they're displayed.

    public function invalidateCell(rowIndex:int, columnIndex:int):void
    {
        if (!dataProvider)
            return;
        
        const dataProviderLength:int = dataProvider.length;
        if (rowIndex >= dataProvider.length)
            return;
        
        if (!isCellVisible(rowIndex, columnIndex))
            return;
        
        // TODO (hmuller) this is a provisional implementation: invalidate the entire row
        
        const column:GridColumn = getGridColumn(columnIndex);
        const dataField:String = (column) ? column.dataField : null;
        
        if (rowIndex >= 0)
        {
            // invalidate the cell or the row by invalidating the visible row
            dataProvider.itemUpdated(dataProvider.getItemAt(rowIndex), dataField);
        }
        else
        {
            // invaliate the column by invalidating all visible rows
            const rowIndices:Vector.<int> = getVisibleRowIndices();
            for each (rowIndex in rowIndices)
            {
                // If there are any padding rows, skip them.
                if (rowIndex >= dataProviderLength)
                    break;
                
                dataProvider.itemUpdated(dataProvider.getItemAt(rowIndex), dataField);          
            }
        }
    }
    
    /**
