--- a/browser/components/search/content/search.xml
+++ b/browser/components/search/content/search.xml
@@ -1122,19 +1122,19 @@
         }
 
         // Show the current default engine in the top header of the panel.
         this.updateHeader();
       ]]></handler>
 
       <handler event="popuphiding"><![CDATA[
         this._isHiding = true;
-        setTimeout(() => {
+        Services.tm.dispatchToMainThread(() => {
           this._isHiding = false;
-        }, 0);
+        });
       ]]></handler>
 
       <!-- This handles clicks on the topmost "Foo Search" header in the
            popup (hbox[anonid="searchbar-engine"]). -->
       <handler event="click"><![CDATA[
         if (event.button == 2) {
           // Ignore right clicks.
           return;