diff --git a/browser/components/customizableui/src/CustomizableUI.jsm b/browser/components/customizableui/src/CustomizableUI.jsm
index 6dd92bb13bb..1453916ff5a 100644
--- a/browser/components/customizableui/src/CustomizableUI.jsm
+++ b/browser/components/customizableui/src/CustomizableUI.jsm
@@ -3704,6 +3704,7 @@ function XULWidgetSingleWrapper(aWidgetId, aNode, aDocument) {
 }
 
 const LAZY_RESIZE_INTERVAL_MS = 200;
+const OVERFLOW_PANEL_HIDE_DELAY_MS = 500
 
 function OverflowableToolbar(aToolbarNode) {
   this._toolbar = aToolbarNode;
@@ -3747,6 +3748,8 @@ OverflowableToolbar.prototype = {
     let chevronId = this._toolbar.getAttribute("overflowbutton");
     this._chevron = doc.getElementById(chevronId);
     this._chevron.addEventListener("command", this);
+    this._chevron.addEventListener("dragover", this);
+    this._chevron.addEventListener("dragend", this);
 
     let panelId = this._toolbar.getAttribute("overflowpanel");
     this._panel = doc.getElementById(panelId);
@@ -3781,6 +3784,8 @@ OverflowableToolbar.prototype = {
     window.gNavToolbox.removeEventListener("customizationstarting", this);
     window.gNavToolbox.removeEventListener("aftercustomization", this);
     this._chevron.removeEventListener("command", this);
+    this._chevron.removeEventListener("dragover", this);
+    this._chevron.removeEventListener("dragend", this);
     this._panel.removeEventListener("popuphiding", this);
     CustomizableUI.removeListener(this);
     CustomizableUIInternal.removePanelCloseListeners(this._panel);
@@ -3788,8 +3793,8 @@ OverflowableToolbar.prototype = {
 
   handleEvent: function(aEvent) {
     switch(aEvent.type) {
-      case "resize":
-        this._onResize(aEvent);
+      case "aftercustomization":
+        this._enable();
         break;
       case "command":
         if (aEvent.target == this._chevron) {
@@ -3798,15 +3803,20 @@ OverflowableToolbar.prototype = {
           this._panel.hidePopup();
         }
         break;
-      case "popuphiding":
-        this._onPanelHiding(aEvent);
-        break;
       case "customizationstarting":
         this._disable();
         break;
-      case "aftercustomization":
-        this._enable();
+      case "dragover":
+        this._showWithTimeout();
         break;
+      case "dragend":
+        this._panel.hidePopup();
+        break;
+      case "popuphiding":
+        this._onPanelHiding(aEvent);
+        break;
+      case "resize":
+        this._onResize(aEvent);
     }
   },
 
@@ -3824,8 +3834,11 @@ OverflowableToolbar.prototype = {
     this._panel.openPopup(anchor || this._chevron);
     this._chevron.open = true;
 
-    this._panel.addEventListener("popupshown", function onPopupShown() {
+    let overflowableToolbarInstance = this;
+    this._panel.addEventListener("popupshown", function onPopupShown(aEvent) {
       this.removeEventListener("popupshown", onPopupShown);
+      this.addEventListener("dragover", overflowableToolbarInstance);
+      this.addEventListener("dragend", overflowableToolbarInstance);
       deferred.resolve();
     });
 
@@ -3843,6 +3856,8 @@ OverflowableToolbar.prototype = {
 
   _onPanelHiding: function(aEvent) {
     this._chevron.open = false;
+    this._panel.removeEventListener("dragover", this);
+    this._panel.removeEventListener("dragend", this);
     let doc = aEvent.target.ownerDocument;
     let contextMenu = doc.getElementById(this._panel.getAttribute("context"));
     gELS.removeSystemEventListener(contextMenu, 'command', this, true);
@@ -4077,6 +4092,21 @@ OverflowableToolbar.prototype = {
     }
     return this._target;
   },
+
+  _hideTimeoutId: null,
+  _showWithTimeout: function() {
+    this.show();
+    let window = this._toolbar.ownerDocument.defaultView;
+    if (this._hideTimeoutId) {
+      window.clearTimeout(this._hideTimeoutId);
+      this._hideTimeoutId = null;
+    }
+    this._hideTimeoutId = window.setTimeout(() => {
+      if (!this._panel.firstChild.mozMatchesSelector(":hover")) {
+        this._panel.hidePopup();
+      }
+    }, OVERFLOW_PANEL_HIDE_DELAY_MS);
+  },
 };
 
 CustomizableUIInternal.initialize();
diff --git a/browser/components/customizableui/test/browser.ini b/browser/components/customizableui/test/browser.ini
index 93fb73b630d..d6f1cd97902 100644
--- a/browser/components/customizableui/test/browser.ini
+++ b/browser/components/customizableui/test/browser.ini
@@ -69,6 +69,7 @@ skip-if = e10s # Bug ?????? - test uses promiseTabLoadEvent() which isn't e10s f
 [browser_948985_non_removable_defaultArea.js]
 [browser_952963_areaType_getter_no_area.js]
 [browser_956602_remove_special_widget.js]
+[browser_962069_drag_to_overflow_chevron.js]
 [browser_962884_opt_in_disable_hyphens.js]
 [browser_963639_customizing_attribute_non_customizable_toolbar.js]
 [browser_967000_button_charEncoding.js]
diff --git a/browser/components/customizableui/test/browser_962069_drag_to_overflow_chevron.js b/browser/components/customizableui/test/browser_962069_drag_to_overflow_chevron.js
new file mode 100644
index 00000000000..aa64875ad8b
--- /dev/null
+++ b/browser/components/customizableui/test/browser_962069_drag_to_overflow_chevron.js
@@ -0,0 +1,39 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+let originalWindowWidth;
+
+// Drag to overflow chevron should open the overflow panel.
+add_task(function*() {
+  originalWindowWidth = window.outerWidth;
+  let navbar = document.getElementById(CustomizableUI.AREA_NAVBAR);
+  ok(!navbar.hasAttribute("overflowing"), "Should start with a non-overflowing toolbar.");
+  ok(CustomizableUI.inDefaultState, "Should start in default state.");
+  let oldChildCount = navbar.customizationTarget.childElementCount;
+  window.resizeTo(400, window.outerHeight);
+  yield waitForCondition(() => navbar.hasAttribute("overflowing"));
+  ok(navbar.hasAttribute("overflowing"), "Should have an overflowing toolbar.");
+
+  let widgetOverflowPanel = document.getElementById("widget-overflow");
+  let panelShownPromise = promisePanelElementShown(window, widgetOverflowPanel);
+  let identityBox = document.getElementById("identity-box");
+  let overflowChevron = document.getElementById("nav-bar-overflow-button");
+  ChromeUtils.synthesizeDrop(identityBox, overflowChevron, [], null);
+  yield panelShownPromise;
+
+  ok(true, "Overflow panel is shown.");
+
+  let panelHiddenPromise = promisePanelElementHidden(window, widgetOverflowPanel);
+  EventUtils.synthesizeKey("VK_ESCAPE", {});
+  yield panelHiddenPromise;
+});
+
+add_task(function*() {
+  window.resizeTo(originalWindowWidth, window.outerHeight);
+  let navbar = document.getElementById(CustomizableUI.AREA_NAVBAR);
+  yield waitForCondition(() => !navbar.hasAttribute("overflowing"));
+  ok(!navbar.hasAttribute("overflowing"), "Should not have an overflowing toolbar.");
+});