diff --git a/browser/components/tabbrowser/content/tabs.js b/browser/components/tabbrowser/content/tabs.js
index 568f3a7cc7051ff8cb569f6bcb8018a5212f7072..b9a1cfe3a4a5035d9b06b0b3826a97c52cfcb39e 100644
--- a/browser/components/tabbrowser/content/tabs.js
+++ b/browser/components/tabbrowser/content/tabs.js
@@ -197,8 +197,12 @@
       XPCOMUtils.defineLazyPreferenceGetter(
         this,
         "_sidebarPositionStart",
-        "sidebar.position_start",
-        true
+        "zen.tabs.vertical.right-side",
+        true,
+        null,
+        newValue => {
+          return !newValue;
+        }
       );
 
       if (gMultiProcessBrowser) {
@@ -220,7 +224,7 @@
 
       this.tooltip = "tabbrowser-tab-tooltip";
 
-      this.tabDragAndDrop = new window.TabDragAndDrop(this);
+      this.tabDragAndDrop = new window.ZenDragAndDrop(this);
       this.tabDragAndDrop.init();
     }
 
@@ -444,7 +448,7 @@
       // and we're not hitting the scroll buttons.
       if (
         event.button != 0 ||
-        event.target != this.arrowScrollbox ||
+        !event.target.classList.contains("zen-workspace-empty-space") ||
         event.composedTarget.localName == "toolbarbutton"
       ) {
         return;
@@ -525,7 +529,6 @@
             });
           }
         } else if (isTabGroupLabel(event.target)) {
-          event.target.group.saveAndClose();
         } else if (
           event.originalTarget.closest("scrollbox") &&
           !Services.prefs.getBoolPref(
@@ -561,6 +564,9 @@
     }
 
     on_keydown(event) {
+      if (document.documentElement.getAttribute('zen-renaming-tab') === 'true') {
+        return;
+      }
       let { altKey, shiftKey } = event;
       let [accel, nonAccel] =
         AppConstants.platform == "macosx"
@@ -755,7 +761,6 @@
       this._updateCloseButtons();
 
       if (!this.#animatingGroups.size) {
-        this._handleTabSelect(true);
       }
 
       document
@@ -822,7 +827,7 @@
     }
 
     get newTabButton() {
-      return this.querySelector("#tabs-newtab-button");
+      return gZenWorkspaces.activeWorkspaceStrip.querySelector("#tabs-newtab-button");
     }
 
     get verticalMode() {
@@ -838,6 +843,7 @@
     }
 
     get overflowing() {
+      gZenWorkspaces.updateOverflowingTabs();
       return this.hasAttribute("overflow");
     }
 
@@ -851,29 +857,56 @@
       if (pinnedChildren?.at(-1)?.id == "pinned-tabs-container-periphery") {
         pinnedChildren.pop();
       }
-      let unpinnedChildren = Array.from(this.arrowScrollbox.children);
+      let unpinnedChildren = gZenWorkspaces.tabboxChildren;
       // remove arrowScrollbox periphery element.
       unpinnedChildren.pop();
 
       // explode tab groups and split view wrappers
       // Iterate backwards over the array to preserve indices while we modify
       // things in place
-      for (let i = unpinnedChildren.length - 1; i >= 0; i--) {
-        if (
-          unpinnedChildren[i].tagName == "tab-group" ||
-          unpinnedChildren[i].tagName == "tab-split-view-wrapper"
-        ) {
-          unpinnedChildren.splice(i, 1, ...unpinnedChildren[i].tabs);
+      const pinnedTabs = [...gZenWorkspaces.getCurrentEssentialsContainer().children, ...pinnedChildren];
+      const expandTabs = (tabs) => {
+        for (let i = tabs.length - 1; i >= 0; i--) {
+          const tab = tabs[i];
+          if (isTabGroup(tab)) {
+            // remove the group from the list
+            tabs.splice(i, 1);
+            // add the tabs in the group to the list
+            tabs.splice(i, 0, ...tab.tabs);
+          } else if (!isTab(tab)) {
+            tabs.splice(i, 1);
+          }
+        }
+      };
+      expandTabs(pinnedTabs);
+      expandTabs(unpinnedChildren);
+      const allTabs = [
+        ...pinnedTabs,
+        ...unpinnedChildren,
+      ];
+      const lastPinnedTabIdx = pinnedTabs.length - 1;
+      let i = 0;
+      for (const tab of [...allTabs]) {
+        // add glance tabs (tabs inside tabs) to the list
+        const glanceTab = tab.glanceTab;
+        if (glanceTab) {
+          // insert right after the parent tab. note: it must be inserted before
+          // the last pinned tab so it can be inserted in the correct order
+          allTabs.splice(Math.max(i++ + 1, lastPinnedTabIdx), 0, glanceTab);
+        } else if (tab.classList.contains("pinned-tabs-container-separator")) {
+          // remove the separator from the list
+          allTabs.splice(i, 1);
+          i--;
         }
+        i++;
       }
-
-      this.#allTabs = [...pinnedChildren, ...unpinnedChildren];
+      this.#allTabs = allTabs;
       return this.#allTabs;
     }
 
     get allGroups() {
       let children = Array.from(this.arrowScrollbox.children);
-      return children.filter(node => node.tagName == "tab-group");
+      return gZenWorkspaces.allTabGroups;
     }
 
     get allSplitViews() {
@@ -958,29 +991,28 @@
         return this.#focusableItems;
       }
 
-      let unpinnedChildren = Array.from(this.arrowScrollbox.children);
-      let pinnedChildren = Array.from(this.pinnedTabsContainer.children);
+      let elementIndex = 0;
+      let children = gZenWorkspaces.tabboxChildrenWithoutEmpty;
 
       let focusableItems = [];
-      for (let child of pinnedChildren) {
-        if (isTab(child)) {
-          focusableItems.push(child);
-        }
-      }
-      for (let child of unpinnedChildren) {
+      for (let child of [...gZenWorkspaces.getCurrentEssentialsContainer().children, ...(gZenWorkspaces.activeWorkspaceElement?.hasCollapsedPinnedTabs ? [] : this.pinnedTabsContainer.children), ...children]) {
         if (isTab(child) && child.visible) {
           focusableItems.push(child);
         } else if (isTabGroup(child)) {
           focusableItems.push(child.labelElement);
-
-          let visibleTabsInGroup = child.tabs.filter(tab => tab.visible);
+        if (!child.hasAttribute("split-view-group")) {
+          let visibleTabsInGroup = child.childGroupsAndTabs.filter(tab => tab.visible);
+          
           focusableItems.push(...visibleTabsInGroup);
+        }
         } else if (child.tagName == "tab-split-view-wrapper") {
           let visibleTabsInSplitView = child.tabs.filter(tab => tab.visible);
           focusableItems.push(...visibleTabsInSplitView);
         }
       }
-
+      focusableItems.forEach(item => {
+        item.elementIndex = elementIndex++;
+      });
       this.#focusableItems = focusableItems;
 
       return this.#focusableItems;
@@ -993,6 +1025,7 @@
      * focusable (ex, we don't want the splitview container to be focusable, only its children).
      */
     get dragAndDropElements() {
+      return this.ariaFocusableItems;
       if (this.#dragAndDropElements) {
         return this.#dragAndDropElements;
       }
@@ -1063,6 +1096,7 @@
     _invalidateCachedTabs() {
       this.#allTabs = null;
       this._invalidateCachedVisibleTabs();
+      gZenWorkspaces._allStoredTabs = null;
     }
 
     _invalidateCachedVisibleTabs() {
@@ -1082,7 +1116,8 @@
 
     isContainerVerticalPinnedGrid(tab) {
       return (
-        tab.pinned &&
+        tab.hasAttribute("zen-essential") &&
+        (this.hasAttribute("expanded") || document.documentElement.hasAttribute("zen-sidebar-expanded")) &&
         this.verticalMode &&
         this.hasAttribute("expanded") &&
         !this.expandOnHover
@@ -1176,7 +1211,7 @@
 
       if (node == null) {
         // We have a container for non-tab elements at the end of the scrollbox.
-        node = this.arrowScrollbox.lastChild;
+        node = gZenWorkspaces.activeWorkspaceStrip.lastChild;
       }
 
       node.before(tab);
@@ -1271,7 +1306,7 @@
           // There are separate "new tab" buttons for horizontal tabs toolbar, vertical tabs and
           // for when the tab strip is overflowed (which is shared by vertical and horizontal tabs);
           // Attach the long click popup to all of them.
-          const newTab = document.getElementById("new-tab-button");
+          const newTab = gZenWorkspaces.activeWorkspaceStrip.querySelector("#tabs-newtab-button");
           const newTab2 = this.newTabButton;
           const newTabVertical = document.getElementById(
             "vertical-tabs-newtab-button"
@@ -1376,8 +1411,10 @@
      */
     _handleTabSelect(aInstant) {
       let selectedTab = this.selectedItem;
+      if (!selectedTab) return;
       this.#ensureTabIsVisible(selectedTab, aInstant);
 
+      gZenCompactModeManager.flashSidebarIfNecessary(aInstant);
       selectedTab._notselectedsinceload = false;
     }
 
@@ -1386,7 +1423,7 @@
      * @param {boolean} [shouldScrollInstantly=false]
      */
     #ensureTabIsVisible(tab, shouldScrollInstantly = false) {
-      let arrowScrollbox = tab.closest("arrowscrollbox");
+      let arrowScrollbox = this.arrowScrollbox;
       if (arrowScrollbox?.overflowing) {
         arrowScrollbox.ensureElementIsVisible(tab, shouldScrollInstantly);
       }
@@ -1513,7 +1550,7 @@
     }
 
     _notifyBackgroundTab(aTab) {
-      if (aTab.pinned || !aTab.visible || !this.overflowing) {
+      if (aTab.hasAttribute("zen-essential") || !aTab.visible || !this.overflowing) {
         return;
       }
 
