     private var _columnWidth:Number = NaN;
 
     [Bindable("propertyChange")]
-    [Inspectable(category="General")]
+    [Inspectable(category="General", minValue="0.0")]
 
     /**
      *  Contain the actual column width.

    private var _rowHeight:Number = NaN;

    [Bindable("propertyChange")]
    [Inspectable(category="General")]

    /**
     *  The row height.

     */
    private var _requestedRowCount:int = -1;
    
    [Inspectable(category="General", minValue="-1")]

    /**
     *  Number of rows to be displayed.
