--- a/devtools/client/framework/toolbox.js
+++ b/devtools/client/framework/toolbox.js
@@ -1402,16 +1402,17 @@ Toolbox.prototype = {
       return deferred.promise;
     }
 
     iframe = this.doc.createElement("iframe");
     iframe.className = "toolbox-panel-iframe";
     iframe.id = "toolbox-panel-iframe-" + id;
     iframe.setAttribute("flex", 1);
     iframe.setAttribute("forceOwnRefreshDriver", "");
+    iframe.setAttribute("useContentEventHandling", "true");
     iframe.tooltip = "aHTMLTooltip";
     iframe.style.visibility = "hidden";
 
     gDevTools.emit(id + "-init", this, iframe);
     this.emit(id + "-init", iframe);
 
     // If no parent yet, append the frame into default location.
     if (!iframe.parentNode) {