diff --git a/browser/base/content/tabbrowser.js b/browser/base/content/tabbrowser.js
index 9058ea6513b3..d6c1ebb797f6 100644
--- a/browser/base/content/tabbrowser.js
+++ b/browser/base/content/tabbrowser.js
@@ -250,19 +250,6 @@ window._gBrowser = {
     return i;
   },
 
-  get popupAnchor() {
-    if (this.selectedTab._popupAnchor) {
-      return this.selectedTab._popupAnchor;
-    }
-    let stack = this.selectedBrowser.parentNode;
-    // Create an anchor for the popup
-    let popupAnchor = document.createXULElement("hbox");
-    popupAnchor.className = "popup-anchor";
-    popupAnchor.hidden = true;
-    stack.appendChild(popupAnchor);
-    return this.selectedTab._popupAnchor = popupAnchor;
-  },
-
   set selectedTab(val) {
     if (gNavToolbox.collapsed && !this._allowTabChange) {
       return this.tabbox.selectedTab;
diff --git a/browser/modules/FormValidationHandler.jsm b/browser/modules/FormValidationHandler.jsm
index d9724f92db41..0e2343744a36 100644
--- a/browser/modules/FormValidationHandler.jsm
+++ b/browser/modules/FormValidationHandler.jsm
@@ -108,7 +108,7 @@ var FormValidationHandler =
     this._panel.hidden = false;
 
     let tabBrowser = aWindow.gBrowser;
-    this._anchor = tabBrowser.popupAnchor;
+    this._anchor = tabBrowser.selectedBrowser.popupAnchor;
     this._anchor.left = aPanelData.contentRect.left;
     this._anchor.top = aPanelData.contentRect.top;
     this._anchor.width = aPanelData.contentRect.width;
diff --git a/toolkit/content/widgets/browser-custom-element.js b/toolkit/content/widgets/browser-custom-element.js
index 0522b614e909..184d58837ae9 100644
--- a/toolkit/content/widgets/browser-custom-element.js
+++ b/toolkit/content/widgets/browser-custom-element.js
@@ -401,6 +401,30 @@ class MozBrowser extends MozElements.MozElementMixin(XULFrameElement) {
     return document.getElementById(this.getAttribute("datetimepicker"));
   }
 
+  /**
+   * Provides a node to hang popups (such as the datetimepicker) from.
+   * If this <browser> isn't the descendant of a <stack>, null is returned
+   * instead and popup code must handle this case.
+   */
+  get popupAnchor() {
+    let stack = this.closest("stack");
+    if (!stack) {
+      return null;
+    }
+
+    let popupAnchor = stack.querySelector(".popup-anchor");
+    if (popupAnchor) {
+      return popupAnchor;
+    }
+
+    // Create an anchor for the popup
+    popupAnchor = document.createXULElement("hbox");
+    popupAnchor.className = "popup-anchor";
+    popupAnchor.hidden = true;
+    stack.appendChild(popupAnchor);
+    return popupAnchor;
+  }
+
   set docShellIsActive(val) {
     if (this.isRemoteBrowser) {
       let { frameLoader } = this;
diff --git a/toolkit/modules/DateTimePickerParent.jsm b/toolkit/modules/DateTimePickerParent.jsm
index 5dc3231a2360..5f07a1ad7621 100644
--- a/toolkit/modules/DateTimePickerParent.jsm
+++ b/toolkit/modules/DateTimePickerParent.jsm
@@ -111,7 +111,11 @@ var DateTimePickerParent = {
     let type = aData.type;
     let detail = aData.detail;
 
-    this._anchor = aBrowser.ownerGlobal.gBrowser.popupAnchor;
+    this._anchor = aBrowser.popupAnchor;
+    if (!this._anchor) {
+      throw new Error("No popup anchor for this browser, cannot show date picker");
+    }
+
     this._anchor.left = rect.left;
     this._anchor.top = rect.top;
     this._anchor.width = rect.width;
@@ -123,7 +127,7 @@ var DateTimePickerParent = {
     let window = aBrowser.ownerGlobal;
     let tabbrowser = window.gBrowser;
     if (Services.focus.activeWindow != window ||
-        tabbrowser.selectedBrowser != aBrowser) {
+        (tabbrowser && tabbrowser.selectedBrowser != aBrowser)) {
       // We were sent a message from a window or tab that went into the
       // background, so we'll ignore it for now.
       return;