diff --git a/browser/base/content/browser-pageActions.js b/browser/base/content/browser-pageActions.js
index d432aec07daf..26f6042e74ee 100644
--- a/browser/base/content/browser-pageActions.js
+++ b/browser/base/content/browser-pageActions.js
@@ -557,7 +557,7 @@ var BrowserPageActions = {
    */
   mainButtonClicked(event) {
     event.stopPropagation();
-    if ((event.type == "click" && event.button != 0) ||
+    if ((event.type == "mousedown" && event.button != 0) ||
         (event.type == "keypress" && event.charCode != KeyEvent.DOM_VK_SPACE &&
          event.keyCode != KeyEvent.DOM_VK_RETURN)) {
       return;
diff --git a/browser/components/customizableui/CustomizableUI.jsm b/browser/components/customizableui/CustomizableUI.jsm
index 246391f6fc6e..774d49d600c8 100644
--- a/browser/components/customizableui/CustomizableUI.jsm
+++ b/browser/components/customizableui/CustomizableUI.jsm
@@ -4230,6 +4230,9 @@ OverflowableToolbar.prototype = {
         this._enable();
         break;
       case "mousedown":
+        if (aEvent.button != 0) {
+          break;
+        }
         if (aEvent.target == this._chevron) {
           this._onClickChevron(aEvent);
         } else {
diff --git a/browser/components/customizableui/content/panelUI.js b/browser/components/customizableui/content/panelUI.js
index 20a7255f975f..24ed29d42c6f 100644
--- a/browser/components/customizableui/content/panelUI.js
+++ b/browser/components/customizableui/content/panelUI.js
@@ -359,6 +359,9 @@ const PanelUI = {
 
     let domEvent = null;
     if (aEvent) {
+      if (aEvent.type == "mousedown" && aEvent.button != 0) {
+        return;
+      }
       if (aEvent.type == "command" && aEvent.inputSource != null) {
         // Synthesize a new DOM mouse event to pass on the inputSource.
         domEvent = document.createEvent("MouseEvent");
diff --git a/browser/components/downloads/content/indicator.js b/browser/components/downloads/content/indicator.js
index abcf3a0a1efe..948d93680d92 100644
--- a/browser/components/downloads/content/indicator.js
+++ b/browser/components/downloads/content/indicator.js
@@ -504,6 +504,10 @@ const DownloadsIndicatorView = {
   },
 
   onCommand(aEvent) {
+    if (aEvent.type == "mousedown" && aEvent.button != 0) {
+      return;
+    }
+
     // If the downloads button is in the menu panel, open the Library
     let widgetGroup = CustomizableUI.getWidget("downloads-button");
     if (widgetGroup.areaType == CustomizableUI.TYPE_MENU_PANEL) {
diff --git a/browser/components/downloads/test/browser/browser_overflow_anchor.js b/browser/components/downloads/test/browser/browser_overflow_anchor.js
index 5135e774194c..503610f21d49 100644
--- a/browser/components/downloads/test/browser/browser_overflow_anchor.js
+++ b/browser/components/downloads/test/browser/browser_overflow_anchor.js
@@ -38,7 +38,7 @@ add_task(async function test_overflow_anchor() {
   await waitForOverflowed(button, true);
 
   let promise = promisePanelOpened();
-  button.node.dispatchEvent(new Event("mousedown"));
+  EventUtils.sendMouseEvent({ type: "mousedown", button: 0 }, button.node);
   await promise;
 
   let panel = DownloadsPanel.panel;
@@ -58,7 +58,7 @@ add_task(async function test_overflow_anchor() {
 
   // Now try opening the panel again.
   promise = promisePanelOpened();
-  button.node.dispatchEvent(new Event("mousedown"));
+  EventUtils.sendMouseEvent({ type: "mousedown", button: 0 }, button.node);
   await promise;
 
   is(panel.anchorNode.id, "downloads-indicator-anchor");