--- a/browser/components/extensions/ext-utils.js
+++ b/browser/components/extensions/ext-utils.js
@@ -240,16 +240,17 @@ class BasePopup {
   createBrowser(viewNode, popupURL = null) {
     let document = viewNode.ownerDocument;
     this.browser = document.createElementNS(XUL_NS, "browser");
     this.browser.setAttribute("type", "content");
     this.browser.setAttribute("disableglobalhistory", "true");
     this.browser.setAttribute("transparent", "true");
     this.browser.setAttribute("class", "webextension-popup-browser");
     this.browser.setAttribute("webextension-view-type", "popup");
+    this.browser.setAttribute("tooltip", "aHTMLTooltip");
 
     // We only need flex sizing for the sake of the slide-in sub-views of the
     // main menu panel, so that the browser occupies the full width of the view,
     // and also takes up any extra height that's available to it.
     this.browser.setAttribute("flex", "1");
 
     // Note: When using noautohide panels, the popup manager will add width and
     // height attributes to the panel, breaking our resize code, if the browser