JavaScript Lesezeichen Manager öffnen geht nicht mehr.

// Bookmarksmanager.uc.js 
// Autor @BrokenHeart aus link-button.uc.js umgeschrieben


(function() {

    if (!window.gBrowser){
        return;
    }

    let newWindow = null;

    try {
       CustomizableUI.createWidget({
          id: 'bookmarks-manager-button',
          type: 'custom',
          defaultArea: CustomizableUI.AREA_NAVBAR,
          onBuild: function(aDocument) {         
            var toolbaritem = aDocument.createXULElement('toolbarbutton');
            var props = {
                id: 'bookmarks-manager-button',
                class: 'toolbarbutton-1 chromeclass-toolbar-additional',
                removable: 'true',
                label: 'Lesezeichen Manager',
                accesskey: 'e',
                tooltiptext: 'Lesezeichen Manager oeffnen',
                style: 'list-style-image: url("data:image/png;base64,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");'
             };            
             for (var p in props)
                toolbaritem.setAttribute(p, props[p]);            
             return toolbaritem; 
          }      
       });
    } catch(e) { };


    document.getElementById('bookmarks-manager-button').addEventListener( 'click', function(event) {		
		    
        if (event.button == 0) 
        {
        
         newWindow = null;
		 
		event.target.ownerGlobal.openTrustedLinkIn('chrome://browser/content/places/places.xhtml',"tab");             
            
        }         
        
    }, true);
    
}) ();