diff --git a/abstract_client.cpp b/abstract_client.cpp
index 393e17bcc0..bc3774d73e 100644
--- a/abstract_client.cpp
+++ b/abstract_client.cpp
@@ -119,6 +119,16 @@ TabGroup *AbstractClient::tabGroup() const
     return nullptr;
 }
 
+void AbstractClient::setTabGroup(TabGroup* group)
+{
+    Q_UNUSED(group)
+}
+
+void AbstractClient::setClientShown(bool shown)
+{
+    Q_UNUSED(shown)
+}
+
 bool AbstractClient::untab(const QRect &toGeometry, bool clientRemoved)
 {
     Q_UNUSED(toGeometry)
diff --git a/abstract_client.h b/abstract_client.h
index 237f3b1c49..c7401a8f83 100644
--- a/abstract_client.h
+++ b/abstract_client.h
@@ -423,6 +423,8 @@ public:
     }
     virtual void setFullScreen(bool set, bool user = true) = 0;
     virtual TabGroup *tabGroup() const;
+    virtual void setTabGroup(TabGroup* group);
+    virtual void setClientShown(bool shown);
     Q_INVOKABLE virtual bool untab(const QRect &toGeometry = QRect(), bool clientRemoved = false);
     virtual bool isCurrentTab() const;
     virtual QRect geometryRestore() const = 0;
diff --git a/client.h b/client.h
index cd13885d0c..288c4b18df 100644
--- a/client.h
+++ b/client.h
@@ -270,14 +270,14 @@ public:
     /**
      * Set tab group - this is to be invoked by TabGroup::add/remove(client) and NO ONE ELSE
      */
-    void setTabGroup(TabGroup* group);
+    void setTabGroup(TabGroup* group) override;
     /*
     *   If shown is true the client is mapped and raised, if false
     *   the client is unmapped and hidden, this function is called
     *   when the tabbing group of the client switches its visible
     *   client.
     */
-    void setClientShown(bool shown);
+    void setClientShown(bool shown) override;
     /*
     *   When a click is done in the decoration and it calls the group
     *   to change the visible client it starts to move-resize the new
diff --git a/tabgroup.cpp b/tabgroup.cpp
index 9cc183a2b6..ee4b287cf7 100644
--- a/tabgroup.cpp
+++ b/tabgroup.cpp
@@ -27,7 +27,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 namespace KWin
 {
 
-TabGroup::TabGroup(Client *c)
+TabGroup::TabGroup(AbstractClient *c)
     : m_clients()
     , m_current(c)
     , m_minSize(c->minSize())
@@ -58,7 +58,7 @@ void TabGroup::activatePrev()
     setCurrent(m_clients.at((index > 0) ? index - 1 : m_clients.count() - 1));
 }
 
-bool TabGroup::add(Client* c, Client *other, bool after, bool becomeVisible)
+bool TabGroup::add(AbstractClient* c, AbstractClient *other, bool after, bool becomeVisible)
 {
     Q_ASSERT(!c->tabGroup());
 
@@ -144,7 +144,7 @@ bool TabGroup::add(Client* c, Client *other, bool after, bool becomeVisible)
     return true;
 }
 
-bool TabGroup::remove(Client* c)
+bool TabGroup::remove(AbstractClient* c)
 {
     if (!c)
         return false;
@@ -189,15 +189,15 @@ void TabGroup::closeAll()
     // after this function exits.
     // However later Wayland support or similar might not share this bahaviour - and we really had
     // enough trouble with a polluted client list around the tabbing code ....
-    ClientList list(m_clients);
-    for (ClientList::const_iterator i = list.constBegin(), end = list.constEnd(); i != end; ++i)
+    auto list(m_clients);
+    for (auto i = list.constBegin(), end = list.constEnd(); i != end; ++i)
         if (*i != m_current)
             (*i)->closeWindow();
 
     m_current->closeWindow();
 }
 
-void TabGroup::move(Client *c, Client *other, bool after)
+void TabGroup::move(AbstractClient *c, AbstractClient *other, bool after)
 {
     if (c == other)
         return;
@@ -222,10 +222,10 @@ void TabGroup::move(Client *c, Client *other, bool after)
 
 bool TabGroup::isActive() const
 {
-    return contains(dynamic_cast<Client*>(Workspace::self()->activeClient()));
+    return contains(Workspace::self()->activeClient());
 }
 
-void TabGroup::setCurrent(Client* c, bool force)
+void TabGroup::setCurrent(AbstractClient* c, bool force)
 {
     if ((c == m_current && !force) || !contains(c))
         return;
@@ -236,18 +236,18 @@ void TabGroup::setCurrent(Client* c, bool force)
 
     m_current = c;
     c->setClientShown(true); // reduce flicker?
-    for (ClientList::const_iterator i = m_clients.constBegin(), end = m_clients.constEnd(); i != end; ++i)
+    for (auto i = m_clients.constBegin(), end = m_clients.constEnd(); i != end; ++i)
         (*i)->setClientShown((*i) == m_current);
 }
 
-void TabGroup::sync(const char *property, Client *c)
+void TabGroup::sync(const char *property, AbstractClient *c)
 {
     if (c->metaObject()->indexOfProperty(property) > -1) {
         qCWarning(KWIN_CORE, "caught attempt to sync non dynamic property: %s", property);
         return;
     }
     QVariant v = c->property(property);
-    for (ClientList::iterator i = m_clients.begin(), end = m_clients.end(); i != end; ++i) {
+    for (auto i = m_clients.begin(), end = m_clients.end(); i != end; ++i) {
         if (*i != m_current)
             (*i)->setProperty(property, v);
     }
@@ -263,7 +263,7 @@ void TabGroup::updateMinMaxSize()
     m_minSize = QSize(0, 0);
     m_maxSize = QSize(INT_MAX, INT_MAX);
 
-    for (ClientList::const_iterator i = m_clients.constBegin(); i != m_clients.constEnd(); ++i) {
+    for (auto i = m_clients.constBegin(); i != m_clients.constEnd(); ++i) {
         m_minSize = m_minSize.expandedTo((*i)->minSize());
         m_maxSize = m_maxSize.boundedTo((*i)->maxSize());
     }
@@ -276,7 +276,7 @@ void TabGroup::updateMinMaxSize()
     const QSize size = m_current->clientSize().expandedTo(m_minSize).boundedTo(m_maxSize);
     if (size != m_current->clientSize()) {
         const QRect r(m_current->pos(), m_current->sizeForClientSize(size));
-        for (ClientList::const_iterator i = m_clients.constBegin(), end = m_clients.constEnd(); i != end; ++i)
+        for (auto i = m_clients.constBegin(), end = m_clients.constEnd(); i != end; ++i)
             (*i)->setGeometry(r);
     }
 }
@@ -290,7 +290,7 @@ void TabGroup::blockStateUpdates(bool more) {
     }
 }
 
-void TabGroup::updateStates(Client* main, States states, Client* only)
+void TabGroup::updateStates(AbstractClient* main, States states, AbstractClient* only)
 {
     if (main == only)
         return; // there's no need to only align "us" to "us"
@@ -302,15 +302,15 @@ void TabGroup::updateStates(Client* main, States states, Client* only)
     states |= m_pendingUpdates;
     m_pendingUpdates = TabGroup::None;
 
-    ClientList toBeRemoved, onlyDummy;
-    ClientList *list = &m_clients;
+    QVector<AbstractClient*> toBeRemoved, onlyDummy;
+    auto *list = &m_clients;
     if (only) {
         onlyDummy << only;
         list = &onlyDummy;
     }
 
-    for (ClientList::const_iterator i = list->constBegin(), end = list->constEnd(); i != end; ++i) {
-        Client *c = (*i);
+    for (auto i = list->constBegin(), end = list->constEnd(); i != end; ++i) {
+        auto *c = (*i);
         if (c != main) {
             if ((states & Minimized) && c->isMinimized() != main->isMinimized()) {
                 if (main->isMinimized())
@@ -353,7 +353,7 @@ void TabGroup::updateStates(Client* main, States states, Client* only)
         }
     }
 
-    for (ClientList::const_iterator i = toBeRemoved.constBegin(), end = toBeRemoved.constEnd(); i != end; ++i)
+    for (auto i = toBeRemoved.constBegin(), end = toBeRemoved.constEnd(); i != end; ++i)
         remove(*i);
 }
 
diff --git a/tabgroup.h b/tabgroup.h
index 5c93907dc6..544910f8c3 100644
--- a/tabgroup.h
+++ b/tabgroup.h
@@ -28,7 +28,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 namespace KWin
 {
 
-class Client;
+class AbstractClient;
 
 /**
  * This class represents a group of clients for use in window tabbing. All
@@ -52,7 +52,7 @@ public:
     /**
      * Creates a new group containing \p c.
      */
-    explicit TabGroup(Client* c);
+    explicit TabGroup(AbstractClient* c);
     ~TabGroup();
 
     enum State {
@@ -87,7 +87,7 @@ public:
     /**
      * Whether client \p c is member of this group
      */
-    bool contains(Client* c) const;
+    bool contains(AbstractClient* c) const;
 
     /**
      * The amount of clients in this group
@@ -107,22 +107,22 @@ public:
     /**
      * Returns the list of all the clients contained in this group in their current order.
      */
-    const ClientList &clients() const;
+    const QVector<AbstractClient*> &clients() const;
 
     /**
      * Returns the currently visible client.
      */
-    Client* current() const;
+    AbstractClient* current() const;
     /**
      * Makes \p c the visible client in the group - force is only used when the window becomes ready for painting.
      * Any other usage just causes pointless action
      */
-    void setCurrent(Client* c, bool force = false);
+    void setCurrent(AbstractClient* c, bool force = false);
 
     /**
      * Alignes the dynamic Qt @param property of all clients to the one of @param c
      */
-    void sync(const char *property, Client *c);
+    void sync(const char *property, AbstractClient *c);
 
     /**
      * Returns combined minimum size of all clients in the group.
@@ -138,7 +138,7 @@ public:
      * \p main as the primary client to copy the settings off. If \p only is set then only
      * that client is updated to match \p main.
      */
-    void updateStates(Client* main, States states, Client* only = NULL);
+    void updateStates(AbstractClient* main, States states, AbstractClient* only = NULL);
 
     /**
      * updates geometry restrictions of this group, basically called from Client::getWmNormalHints(), otherwise rather private
@@ -152,21 +152,21 @@ Q_SIGNALS:
 private:
     friend class Client;
 //     friend bool Client::tabTo(Client*, bool, bool);
-    bool add(KWin::Client *c, Client *other, bool behind, bool activateC);
-    void move(KWin::Client* c, KWin::Client* before, bool behind);
+    bool add(KWin::AbstractClient *c, AbstractClient *other, bool behind, bool activateC);
+    void move(KWin::AbstractClient* c, KWin::AbstractClient* before, bool behind);
 
 //     friend bool Client::untab(const QRect&);
-    bool remove(KWin::Client *c);
+    bool remove(KWin::AbstractClient *c);
 
-    ClientList m_clients;
-    Client *m_current;
+    QVector<AbstractClient*> m_clients;
+    AbstractClient *m_current;
     QSize m_minSize;
     QSize m_maxSize;
     int m_stateUpdatesBlocked;
     States m_pendingUpdates;
 };
 
-inline bool TabGroup::contains(Client* c) const
+inline bool TabGroup::contains(AbstractClient* c) const
 {
     return c && m_clients.contains(c);
 }
@@ -176,7 +176,7 @@ inline int TabGroup::count() const
     return m_clients.count();
 }
 
-inline const ClientList &TabGroup::clients() const
+inline const QVector<AbstractClient*> &TabGroup::clients() const
 {
     return m_clients;
 }
@@ -186,7 +186,7 @@ inline bool TabGroup::isEmpty() const
     return m_clients.isEmpty();
 }
 
-inline Client* TabGroup::current() const
+inline AbstractClient* TabGroup::current() const
 {
     return m_current;
 }
diff --git a/useractions.cpp b/useractions.cpp
index 59344685a7..71219dd319 100644
--- a/useractions.cpp
+++ b/useractions.cpp
@@ -534,7 +534,7 @@ void UserActionsMenu::rebuildTabListPopup()
 
     m_switchToTabMenu->addSeparator();
 
-    for (QList<Client*>::const_iterator i = m_client.data()->tabGroup()->clients().constBegin(),
+    for (auto i = m_client.data()->tabGroup()->clients().constBegin(),
                                         end = m_client.data()->tabGroup()->clients().constEnd(); i != end; ++i) {
         if ((*i)->noBorder() || *i == m_client.data()->tabGroup()->current())
             continue; // cannot tab there anyway