     //----------------------------------
     
     [Bindable("propertyChange")]
-    [Inspectable(category="General")]
+    [Inspectable(category="General", minValue="0.0")]
 
     /**
      *  @copy spark.layouts.TileLayout#rowHeight

    //  horizontalAlign
    //----------------------------------
    
    [Inspectable(category="General", enumeration="left,center,right,justify,contentJustify", defaultValue="left")]

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

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

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