Improve update of canvas item in case of size changes. Maybe fixes bug #2929

git-svn-id: http://svn.osgeo.org/qgis/trunk@14234 c8812cc2-4d05-0410-92ff-de0c093fc19c

src/gui/qgsmapcanvasitem.cpp

@@ -78,10 +78,8 @@ void QgsMapCanvasItem::setRect( const QgsRectangle& rect )
     r = r.normalized();
   }
 
-  // update the point prior to changing its position
-  update();
-
   // set position in canvas where the item will have coordinate (0,0)
+  prepareGeometryChange();
   setPos( r.topLeft() );
   mItemSize = QSizeF( r.width() + 2, r.height() + 2 );