     //  requestedColumnCount
     //----------------------------------
 
-    [Inspectable(category="General")]
+    [Inspectable(category="General", minValue="-1")]
 
     /**
      *  @copy spark.layouts.TileLayout#requestedColumnCount

    //  requestedRowCount
    //----------------------------------

    [Inspectable(category="General")]

    /**
     *  @copy spark.layouts.TileLayout#requestedRowCount

    //----------------------------------
    
    [Bindable("propertyChange")]
    [Inspectable(category="General", minValue="0.0")]

    /**
     *  @copy spark.layouts.TileLayout#columnWidth
