don't crash when clicking on [+]

svn path=/trunk/KDE/kdegraphics/kpdf/; revision=421335

ui/toc.cpp

@@ -120,7 +120,11 @@ void TOC::addChildren( const QDomNode & parentNode, KListViewItem * parentItem )
 
 void TOC::slotExecuted( QListViewItem *i )
 {
-    const QDomElement & e = static_cast< TOCItem* >( i )->element();
+    TOCItem* tocItem = dynamic_cast<TOCItem*>( i );
+    // that filters clicks on [+] that for a strange reason don't seem to be TOCItem*
+    if (tocItem == NULL)
+        return;
+    const QDomElement & e = tocItem->element();
     if ( e.hasAttribute( "Viewport" ) )
     {
         // if the node has a viewport, set it