How can I hide "start a conversation" button using mozilla.cfg

Hi, I've just updated to FF 41.02 and my mozilla.cfg doesn't hide the smiley face icon (Start a conversation). Does anyone know how I can do this? here is the line I use from my mozilla.cfg to show/hide these icons lockPref("browser.uiCustomization.state", "{"placements":{"PanelUI-contents":["edit-controls","downloads-button","new-window-button","privatebrowsing-button","zoom-controls","developer-button","fullscreen-button","preferences-button","history-panelmenu","save-page-button","find-button","add-ons-button","loop-button"],"addon-bar":["addonbar-closebutton","status-bar"],"PersonalToolbar":[],"nav-bar":["urlbar-container","search-container","print-button","home-button"],"TabsToolbar":["tabbrowser-tabs","new-tab-button","alltabs-button"],"toolbar-menubar":["menubar-items"]},"seen":[],"dirtyAreaCache":["PersonalToolbar","nav-bar","TabsToolbar","toolbar-menubar","PanelUI-contents"],"currentVersion":4,"newElementCount":0}"); Thanks