--- a/browser/modules/TabsList.jsm
+++ b/browser/modules/TabsList.jsm
@@ -62,35 +62,26 @@ class TabsListBase {
   /*
    * Populate the popup with menuitems and setup the listeners.
    */
   _populate(event) {
     let fragment = this.doc.createDocumentFragment();
 
     for (let tab of this.gBrowser.tabs) {
       if (this.filterFn(tab)) {
-        let row = this._createRow(tab);
-        row.tab = tab;
-        row.addEventListener("command", this);
-        this.tabToElement.set(tab, row);
-        if (this.className) {
-          row.classList.add(this.className);
-        }
-
-        fragment.appendChild(row);
+        fragment.appendChild(this._createRow(tab));
       }
     }
 
-    if (this.insertBefore) {
-      this.insertBefore.parentNode.insertBefore(fragment, this.insertBefore);
-    } else {
-      this.containerNode.appendChild(fragment);
-    }
+    this._addElement(fragment);
+    this._setupListeners();
+  }
 
-    this._setupListeners();
+  _addElement(elementOrFragment) {
+    this.containerNode.insertBefore(elementOrFragment, this.insertBefore);
   }
 
   /*
    * Remove the menuitems from the DOM, cleanup internal state and listeners.
    */
   _cleanup() {
     for (let item of this.rows) {
       item.remove();
@@ -110,21 +101,42 @@ class TabsListBase {
     this.gBrowser.tabContainer.removeEventListener("TabClose", this);
     this.listenersRegistered = false;
   }
 
   _tabAttrModified(tab) {
     let item = this.tabToElement.get(tab);
     if (item) {
       if (!this.filterFn(tab)) {
-        // If the tab is no longer in this set of tabs, hide the item.
+        // The tab no longer matches our criteria, remove it.
         this._removeItem(item, tab);
       } else {
         this._setRowAttributes(item, tab);
       }
+    } else if (this.filterFn(tab)) {
+      // The tab now matches our criteria, add a row for it.
+      this._addTab(tab);
+    }
+  }
+
+  _addTab(newTab) {
+    let newRow = this._createRow(newTab);
+    let nextTab = newTab.nextSibling;
+
+    while (nextTab && !this.filterFn(nextTab)) {
+      nextTab = nextTab.nextSibling;
+    }
+
+    if (nextTab) {
+      // If we found a tab after this one in the list, insert the new row before it.
+      let nextRow = this.tabToElement.get(nextTab);
+      nextRow.parentNode.insertBefore(newRow, nextRow);
+    } else {
+      // If there's no next tab then insert it as usual.
+      this._addElement(newRow);
     }
   }
 
   _tabClose(tab) {
     let item = this.tabToElement.get(tab);
     if (item) {
       this._removeItem(item, tab);
     }
@@ -201,16 +213,22 @@ class TabsPanel extends TabsListBase {
     super._cleanupListeners();
     this.panelMultiView.removeEventListener(TABS_PANEL_EVENTS.hide, this);
   }
 
   _createRow(tab) {
     let {doc} = this;
     let row = doc.createElementNS(NSXUL, "toolbaritem");
     row.setAttribute("class", "all-tabs-item");
+    if (this.className) {
+      row.classList.add(this.className);
+    }
+    row.tab = tab;
+    row.addEventListener("command", this);
+    this.tabToElement.set(tab, row);
 
     let button = doc.createElementNS(NSXUL, "toolbarbutton");
     button.setAttribute("class", "all-tabs-button subviewbutton subviewbutton-iconic");
     button.setAttribute("flex", "1");
     button.setAttribute("crop", "right");
     button.tab = tab;
 
     row.appendChild(button);