diff --git a/CMakeLists.txt b/CMakeLists.txt
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -272,6 +272,10 @@
 option(KWIN_BUILD_XRENDER_COMPOSITING "Enable building of KWin with XRender Compositing support" ON)
 cmake_dependent_option(KWIN_BUILD_ACTIVITIES "Enable building of KWin with kactivities support" ON "KF5Activities_FOUND" OFF)
 
+# TODO FIXME was off in the 5.1 branch
+option(KWIN_BUILD_KAPPMENU "Enable building of KWin with application menu support" ON)
+# cmake_dependent_option(KWIN_BUILD_KAPPMENU "Build without appmenu support" ON "KWIN_BUILD_DECORATIONS" FALSE)
+
 # Binary name of KWin
 set(KWIN_NAME "kwin")
 set(KWIN_INTERNAL_NAME_X11 "kwin_x11")
@@ -439,6 +443,17 @@
     )
 endif()
 
+if(KWIN_BUILD_KAPPMENU)
+    set(
+        kwin_KDEINIT_SRCS ${kwin_KDEINIT_SRCS}
+        appmenu.cpp
+    )
+    qt5_add_dbus_interface(kwin_KDEINIT_SRCS
+        # FIXME TODO figure out all the cmake magic
+        /home/kaiuwe/Projekte/kf5/plasma-workspace/appmenu/org.kde.kappmenu.xml appmenu_interface)
+        #${CMAKE_SOURCE_DIR}/plasma-workspace/appmenu/org.kde.kappmenu.xml appmenu_interface)
+endif()
+
 if(UDEV_FOUND)
     set(kwin_KDEINIT_SRCS
         ${kwin_KDEINIT_SRCS}
diff --git a/abstract_client.h b/abstract_client.h
--- a/abstract_client.h
+++ b/abstract_client.h
@@ -244,6 +244,11 @@
      * Because of that there is no notify signal.
      **/
     Q_PROPERTY(bool resizeable READ isResizable)
+
+    // FIXME TODO documentation
+    // FIXME TODO should there be a WRITE accessor?
+    Q_PROPERTY(bool applicationMenuAvailable READ applicationMenuAvailable WRITE setApplicationMenuAvailable)
+
 public:
     virtual ~AbstractClient();
 
@@ -583,6 +588,14 @@
     // TODO: remove boolean trap
     static bool belongToSameApplication(const AbstractClient* c1, const AbstractClient* c2, bool active_hack = false);
 
+#ifdef KWIN_BUILD_KAPPMENU
+    void setApplicationMenuAvailable(bool applicationMenuAvailable);
+    void showApplicationMenu(const QPoint &p);
+    bool applicationMenuAvailable() const {
+        return m_applicationMenuAvailable;
+    }
+#endif
+
 public Q_SLOTS:
     virtual void closeWindow() = 0;
 
@@ -622,6 +635,11 @@
     void shadeableChanged(bool);
     void maximizeableChanged(bool);
 
+    void requestShowApplicationMenu();
+    void applicationMenuVisibleChanged(bool applicationMenuVisible);
+
+    void applicationMenuAvailableChanged(bool applicationMenuAvailable);
+
 protected:
     AbstractClient();
     void setFirstInTabBox(bool enable) {
@@ -966,8 +984,12 @@
         QElapsedTimer doubleClickTimer;
     } m_decoration;
 
-
     static bool s_haveResizeEffect;
+
+#ifdef KWIN_BUILD_KAPPMENU
+    bool m_applicationMenuAvailable = false;
+#endif
+
 };
 
 /**
diff --git a/abstract_client.cpp b/abstract_client.cpp
--- a/abstract_client.cpp
+++ b/abstract_client.cpp
@@ -18,6 +18,9 @@
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
 #include "abstract_client.h"
+#ifdef KWIN_BUILD_KAPPMENU
+#include "appmenu.h"
+#endif
 #include "decorations/decoratedclient.h"
 #include "decorations/decorationpalette.h"
 #include "decorations/decorationbridge.h"
@@ -1635,4 +1638,19 @@
     return Toplevel::inputGeometry();
 }
 
+#ifdef KWIN_BUILD_KAPPMENU
+void AbstractClient::setApplicationMenuAvailable(bool applicationMenuAvailable)
+{
+    if (m_applicationMenuAvailable != applicationMenuAvailable) {
+        m_applicationMenuAvailable = applicationMenuAvailable;
+        emit applicationMenuAvailableChanged(applicationMenuAvailable);
+    }
+}
+
+void AbstractClient::showApplicationMenu(const QPoint &p)
+{
+    ApplicationMenu::self()->showApplicationMenu(p, window());
+}
+#endif
+
 }
diff --git a/appmenu.h b/appmenu.h
new file mode 100644
--- /dev/null
+++ b/appmenu.h
@@ -0,0 +1,62 @@
+/********************************************************************
+ KWin - the KDE window manager
+ This file is part of the KDE project.
+
+Copyright (c) 2011 Lionel Chauvin <megabigbug@yahoo.fr>
+Copyright (c) 2011,2012 Cédric Bellegarde <gnumdk@gmail.com>
+Copyright (C) 2013 Martin Gräßlin <mgraesslin@kde.org>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*********************************************************************/
+#ifndef KWIN_APPLICATIONMENU_H
+#define KWIN_APPLICATIONMENU_H
+// KWin
+#include <kwinglobals.h>
+// Qt
+#include <QObject>
+// xcb
+#include <xcb/xcb.h>
+
+class QPoint;
+class OrgKdeKappmenuInterface;
+
+namespace KWin
+{
+
+class ApplicationMenu : public QObject
+{
+    Q_OBJECT
+
+public:
+    virtual ~ApplicationMenu();
+
+    bool hasMenu(xcb_window_t window);
+    void showApplicationMenu(const QPoint &pos, const xcb_window_t window);
+
+private Q_SLOTS:
+    void slotShowRequest(qulonglong wid);
+    void slotMenuAvailable(qulonglong wid);
+    void slotMenuHidden(qulonglong wid);
+    void slotClearMenus();
+
+private:
+    QList<xcb_window_t> m_windowsMenu;
+    OrgKdeKappmenuInterface *m_appmenuInterface;
+
+    KWIN_SINGLETON(ApplicationMenu)
+};
+
+}
+
+#endif // KWIN_APPLICATIONMENU_H
diff --git a/appmenu.cpp b/appmenu.cpp
new file mode 100644
--- /dev/null
+++ b/appmenu.cpp
@@ -0,0 +1,92 @@
+/********************************************************************
+ KWin - the KDE window manager
+ This file is part of the KDE project.
+
+Copyright (c) 2011 Lionel Chauvin <megabigbug@yahoo.fr>
+Copyright (c) 2011,2012 Cédric Bellegarde <gnumdk@gmail.com>
+Copyright (C) 2013 Martin Gräßlin <mgraesslin@kde.org>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*********************************************************************/
+#include "appmenu.h"
+#include "client.h"
+#include "workspace.h"
+#include <appmenu_interface.h>
+
+namespace KWin {
+
+KWIN_SINGLETON_FACTORY(ApplicationMenu)
+
+ApplicationMenu::ApplicationMenu(QObject *parent)
+    : QObject(parent)
+    , m_appmenuInterface(new OrgKdeKappmenuInterface(QStringLiteral("org.kde.kappmenu"), QStringLiteral("/KAppMenu"), QDBusConnection::sessionBus(), this))
+{
+    connect(m_appmenuInterface, &OrgKdeKappmenuInterface::showRequest, this, &ApplicationMenu::slotShowRequest);
+    connect(m_appmenuInterface, &OrgKdeKappmenuInterface::menuAvailable, this, &ApplicationMenu::slotMenuAvailable);
+    connect(m_appmenuInterface, &OrgKdeKappmenuInterface::menuHidden, this, &ApplicationMenu::slotMenuHidden);
+    connect(m_appmenuInterface, &OrgKdeKappmenuInterface::clearMenus, this, &ApplicationMenu::slotClearMenus);
+}
+
+ApplicationMenu::~ApplicationMenu()
+{
+    s_self = nullptr;
+}
+
+bool ApplicationMenu::hasMenu(xcb_window_t window)
+{
+    return m_windowsMenu.removeOne(window);
+}
+
+void ApplicationMenu::slotShowRequest(qulonglong wid)
+{
+    if (Client *c = Workspace::self()->findClient(Predicate::WindowMatch, wid)) {
+        qDebug() << "slot show request" << wid;
+        emit c->requestShowApplicationMenu();
+    }
+}
+
+void ApplicationMenu::slotMenuAvailable(qulonglong wid)
+{
+    if (Client *c = Workspace::self()->findClient(Predicate::WindowMatch, wid)) {
+        c->setApplicationMenuAvailable(true);
+    } else {
+        m_windowsMenu.append(wid);
+    }
+}
+
+void ApplicationMenu::slotMenuHidden(qulonglong wid)
+{
+    if (Client *c = Workspace::self()->findClient(Predicate::WindowMatch, wid)) {
+        emit c->applicationMenuVisibleChanged(false);
+    }
+}
+
+void ApplicationMenu::slotClearMenus()
+{
+    // FIXME TODO qAsConst
+    const auto &clients = Workspace::self()->clientList();
+    for (Client *c : clients) {
+        c->setApplicationMenuAvailable(false);
+    }
+}
+
+void ApplicationMenu::showApplicationMenu(const QPoint &p, const xcb_window_t id)
+{
+    //if (Client *c = Workspace::self()->findClient(Predicate::WindowMatch, wid)) {
+        m_appmenuInterface->showMenu(p.x(), p.y(), id);
+//        emit c->applicationMenuVisibleChanged(true);
+//    }
+}
+
+} // namespace
diff --git a/config-kwin.h.cmake b/config-kwin.h.cmake
--- a/config-kwin.h.cmake
+++ b/config-kwin.h.cmake
@@ -1,6 +1,7 @@
 #cmakedefine KWIN_BUILD_DECORATIONS 1
 #cmakedefine KWIN_BUILD_TABBOX 1
 #cmakedefine KWIN_BUILD_ACTIVITIES 1
+#cmakedefine KWIN_BUILD_KAPPMENU 1
 #define KWIN_NAME "${KWIN_NAME}"
 #define KWIN_INTERNAL_NAME_X11 "${KWIN_INTERNAL_NAME_X11}"
 #define KWIN_CONFIG "${KWIN_NAME}rc"
diff --git a/decorations/decoratedclient.h b/decorations/decoratedclient.h
--- a/decorations/decoratedclient.h
+++ b/decorations/decoratedclient.h
@@ -69,16 +69,22 @@
 
     Qt::Edges adjacentScreenEdges() const override;
 
+    bool isApplicationMenuAvailable() const;
+    bool isApplicationMenuVisible() const;
+
     void requestClose() override;
     void requestContextHelp() override;
     void requestToggleMaximization(Qt::MouseButtons buttons) override;
     void requestMinimize() override;
     void requestShowWindowMenu() override;
+    void requestShowApplicationMenu(const QRect &rect) override;
     void requestToggleKeepAbove() override;
     void requestToggleKeepBelow() override;
     void requestToggleOnAllDesktops() override;
     void requestToggleShade() override;
 
+    void showApplicationMenu();
+
     AbstractClient *client() {
         return m_client;
     }
diff --git a/decorations/decoratedclient.cpp b/decorations/decoratedclient.cpp
--- a/decorations/decoratedclient.cpp
+++ b/decorations/decoratedclient.cpp
@@ -110,6 +110,12 @@
     connect(client, &AbstractClient::maximizeableChanged, decoratedClient, &KDecoration2::DecoratedClient::maximizeableChanged);
 
     connect(client, &AbstractClient::paletteChanged, decoratedClient, &KDecoration2::DecoratedClient::paletteChanged);
+
+#ifdef KWIN_BUILD_KAPPMENU
+    connect(client, &AbstractClient::requestShowApplicationMenu, decoratedClient, &KDecoration2::DecoratedClient::showApplicationMenu);
+    connect(client, &AbstractClient::applicationMenuAvailableChanged, decoratedClient, &KDecoration2::DecoratedClient::applicationMenuAvailableChanged);
+    connect(client, &AbstractClient::applicationMenuVisibleChanged, decoratedClient, &KDecoration2::DecoratedClient::applicationMenuVisibleChanged);
+#endif
 }
 
 DecoratedClientImpl::~DecoratedClientImpl() = default;
@@ -203,6 +209,16 @@
     Workspace::self()->showWindowMenu(QRect(Cursor::pos(), Cursor::pos()), m_client);
 }
 
+void DecoratedClientImpl::requestShowApplicationMenu(const QRect &rect)
+{
+    Workspace::self()->showApplicationMenu(rect, m_client);
+}
+
+void DecoratedClientImpl::showApplicationMenu()
+{
+    m_client->requestShowApplicationMenu();
+}
+
 void DecoratedClientImpl::requestToggleMaximization(Qt::MouseButtons buttons)
 {
     QMetaObject::invokeMethod(this, "delayedRequestToggleMaximization", Qt::QueuedConnection, Q_ARG(Options::WindowOperation, options->operationMaxButtonClick(buttons)));
@@ -265,6 +281,16 @@
     return edges;
 }
 
+bool DecoratedClientImpl::isApplicationMenuAvailable() const
+{
+    return m_client->applicationMenuAvailable();
+}
+
+bool DecoratedClientImpl::isApplicationMenuVisible() const
+{
+    return false; // FIXME TODO we don't track state currently
+}
+
 void DecoratedClientImpl::createRenderer()
 {
     if (Compositor::self()->hasScene()) {
diff --git a/kcmkwin/kwindecoration/declarative-plugin/previewclient.h b/kcmkwin/kwindecoration/declarative-plugin/previewclient.h
--- a/kcmkwin/kwindecoration/declarative-plugin/previewclient.h
+++ b/kcmkwin/kwindecoration/declarative-plugin/previewclient.h
@@ -97,6 +97,10 @@
     QColor color(ColorGroup group, ColorRole role) const override;
     Qt::Edges adjacentScreenEdges() const override;
 
+    // FIXME TODO find a place to put that into the cpp :)
+    bool isApplicationMenuAvailable() const override { return false; }
+    bool isApplicationMenuVisible() const override { return false; }
+
     void requestClose() override;
     void requestContextHelp() override;
     void requestToggleMaximization(Qt::MouseButtons buttons) override;
@@ -105,8 +109,11 @@
     void requestToggleKeepBelow() override;
     void requestToggleShade() override;
     void requestShowWindowMenu() override;
+    void requestShowApplicationMenu(const QRect &rect) override;
     void requestToggleOnAllDesktops() override;
 
+    void showApplicationMenu();
+
     void setCaption(const QString &caption);
     void setActive(bool active);
     void setCloseable(bool closeable);
@@ -176,6 +183,7 @@
     void bordersBottomEdgeChanged(bool);
 
     void showWindowMenuRequested();
+    void showApplicationMenuRequested();
     void minimizeRequested();
     void closeRequested();
 
diff --git a/kcmkwin/kwindecoration/declarative-plugin/previewclient.cpp b/kcmkwin/kwindecoration/declarative-plugin/previewclient.cpp
--- a/kcmkwin/kwindecoration/declarative-plugin/previewclient.cpp
+++ b/kcmkwin/kwindecoration/declarative-plugin/previewclient.cpp
@@ -408,6 +408,17 @@
     emit showWindowMenuRequested();
 }
 
+void PreviewClient::requestShowApplicationMenu(const QRect &rect)
+{
+    Q_UNUSED(rect);
+    emit showApplicationMenuRequested(); // FIXME TODO pass geometry
+}
+
+void PreviewClient::showApplicationMenu()
+{
+
+}
+
 void PreviewClient::requestToggleOnAllDesktops()
 {
     setDesktop(isOnAllDesktops() ? 1 : -1);
diff --git a/useractions.cpp b/useractions.cpp
--- a/useractions.cpp
+++ b/useractions.cpp
@@ -45,6 +45,9 @@
 #include "activities.h"
 #include <kactivities/info.h>
 #endif
+#ifdef KWIN_BUILD_KAPPMENU
+#include "appmenu.h"
+#endif
 
 #include <KProcess>
 
@@ -1670,6 +1673,12 @@
     m_userActionsMenu->show(pos, cl);
 }
 
+void Workspace::showApplicationMenu(const QRect &pos, AbstractClient *c)
+{
+    // FIXME TODO map to global properly, taking into account margins and what not
+    ApplicationMenu::self()->showApplicationMenu(c->geometry().topLeft() + pos.bottomLeft(), c->window());
+}
+
 /*!
   Closes the popup client
  */
diff --git a/workspace.h b/workspace.h
--- a/workspace.h
+++ b/workspace.h
@@ -285,6 +285,8 @@
         return m_userActionsMenu;
     }
 
+    void showApplicationMenu(const QRect &pos, AbstractClient *c);
+
     void updateMinimizedOfTransients(AbstractClient*);
     void updateOnAllDesktopsOfTransients(AbstractClient*);
     void checkTransients(xcb_window_t w);
diff --git a/workspace.cpp b/workspace.cpp
--- a/workspace.cpp
+++ b/workspace.cpp
@@ -27,6 +27,9 @@
 #ifdef KWIN_BUILD_ACTIVITIES
 #include "activities.h"
 #endif
+#ifdef KWIN_BUILD_KAPPMENU
+#include "appmenu.h"
+#endif
 #include "atoms.h"
 #include "client.h"
 #include "composite.h"
@@ -128,6 +131,10 @@
     // If KWin was already running it saved its configuration after loosing the selection -> Reread
     QFuture<void> reparseConfigFuture = QtConcurrent::run(options, &Options::reparseConfiguration);
 
+#ifdef KWIN_BUILD_KAPPMENU
+    ApplicationMenu::create(this);
+#endif
+
     _self = this;
 
     // first initialize the extensions
@@ -578,6 +585,11 @@
     if (TabBox::TabBox::self()->isDisplayed())
         TabBox::TabBox::self()->reset(true);
 #endif
+#ifdef KWIN_BUILD_KAPPMENU
+    if (ApplicationMenu::self()->hasMenu(c->window())) {
+        c->setApplicationMenuAvailable(true);
+    }
+#endif
 }
 
 void Workspace::addUnmanaged(Unmanaged* c)