rem: aEvent.preventBubble(); 
add: if (aEvent) aEvent.preventBubble(); 
context:   open: function (aEvent, aRDFNode)   {     var urlValue = LITERAL(this.db, aRDFNode, NC_NS + "URL");        // Ignore "NC:" and empty urls.    if (urlValue.substring(0,3) == "NC:" || !urlValue) return;        if (aEvent.altKey)         this.showPropertiesForNode (aRDFNode);    else if (this.openNewWindow)      openDialog (getBrowserURL(), "_blank", "chrome,all,dialog=no", urlValue);    else      openTopWin (urlValue);    aEvent.preventBubble();  },
meta: 10234	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/10234/3c1e4cee57d48dad81a4af4b045f5845fa04b0f0/bookmarksOverlay.js/clean/xpfe/components/bookmarks/resources/bookmarksOverlay.js