diff --git a/abstract_client.h b/abstract_client.h
--- a/abstract_client.h
+++ b/abstract_client.h
@@ -333,11 +333,11 @@
      **/
     void setActive(bool);
 
-    bool keepAbove() const {
+    bool keepAbove() const override {
         return m_keepAbove;
     }
     void setKeepAbove(bool);
-    bool keepBelow() const {
+    bool keepBelow() const override {
         return m_keepBelow;
     }
     void setKeepBelow(bool);
@@ -361,7 +361,7 @@
      * @see captionNormal
      * @see captionSuffix
      **/
-    QString caption() const;
+    QString caption() const override final;
     /**
      * @returns The caption as set by the AbstractClient without any suffix.
      * @see caption
@@ -382,7 +382,6 @@
     virtual void hideClient(bool hide) = 0;
     bool isFullScreenable() const;
     bool isFullScreenable(bool fullscreen_hack) const;
-    virtual bool isFullScreen() const = 0;
     // TODO: remove boolean trap
     virtual AbstractClient *findModal(bool allow_itself = false) = 0;
     virtual bool isTransient() const;
@@ -432,7 +431,7 @@
     */
     void minimize(bool avoid_animation = false);
     void unminimize(bool avoid_animation = false);
-    bool isMinimized() const {
+    bool isMinimized() const override {
         return m_minimized;
     }
     virtual void setFullScreen(bool set, bool user = true) = 0;
@@ -458,12 +457,7 @@
     void setTabGroup(TabGroup* group);
     virtual void setClientShown(bool shown);
     Q_INVOKABLE bool untab(const QRect &toGeometry = QRect(), bool clientRemoved = false);
-    /*
-    *   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
-    *   client, this function stops it.
-    */
-    bool isCurrentTab() const;
+    bool isCurrentTab() const override;
     virtual QRect geometryRestore() const = 0;
     /**
      * The currently applied maximize mode
@@ -628,8 +622,7 @@
     virtual bool hasStrut() const;
 
     void setModal(bool modal);
-    bool isModal() const;
-
+    bool isModal() const override;
     /**
      * Determines the mouse command for the given @p button in the current state.
      *
@@ -763,7 +756,6 @@
     void clientUnminimized(KWin::AbstractClient* client, bool animate);
     void paletteChanged(const QPalette &p);
     void colorSchemeChanged();
-    void captionChanged();
     void clientMaximizedStateChanged(KWin::AbstractClient*, MaximizeMode);
     void clientMaximizedStateChanged(KWin::AbstractClient* c, bool h, bool v);
     void transientChanged();
diff --git a/autotests/test_window_paint_data.cpp b/autotests/test_window_paint_data.cpp
--- a/autotests/test_window_paint_data.cpp
+++ b/autotests/test_window_paint_data.cpp
@@ -28,28 +28,6 @@
 
 using namespace KWin;
 
-class MockEffectWindowHelper : public QObject
-{
-    Q_OBJECT
-    Q_PROPERTY(qreal opacity READ opacity WRITE setOpacity)
-public:
-    MockEffectWindowHelper(QObject *parent = nullptr);
-    double opacity() const {
-        return m_opacity;
-    }
-    void setOpacity(qreal opacity) {
-        m_opacity = opacity;
-    }
-private:
-    qreal m_opacity;
-};
-
-MockEffectWindowHelper::MockEffectWindowHelper(QObject *parent)
-    : QObject(parent)
-    , m_opacity(1.0)
-{
-}
-
 class MockEffectWindow : public EffectWindow
 {
     Q_OBJECT
@@ -72,6 +50,185 @@
     virtual void setData(int role, const QVariant &data);
     virtual void referencePreviousWindowPixmap() {}
     virtual void unreferencePreviousWindowPixmap() {}
+
+    bool isDeleted() const override {
+        return false;
+    };
+    bool isMinimized() const override {
+        return false;
+    }
+    double opacity() const override {
+        return m_opacity;
+    }
+    void setOpacity(qreal opacity) {
+        m_opacity = opacity;
+    }
+    bool hasAlpha() const override {
+        return true;
+    }
+    QStringList activities() const override {
+        return QStringList();
+    }
+    int desktop() const override {
+        return 0;
+    }
+    int x() const override {
+        return 0;
+    }
+    int y() const override {
+        return 0;
+    }
+    int width() const override {
+        return 100;
+    }
+    int height() const override {
+        return 100;
+    }
+
+    QSize basicUnit() const override {
+        return QSize();
+    }
+    QRect geometry() const override {
+        return QRect();
+    }
+
+    QRect expandedGeometry() const override {
+        return QRect();
+    }
+    int screen() const override {
+        return 0;
+    };
+    bool hasOwnShape() const override {
+        return false;
+    }
+    QPoint pos() const override {
+        return QPoint();
+    }
+    QSize size() const override {
+        return QSize(100,100);
+    }
+    QRect rect() const override {
+        return QRect(0,0,100,100);
+    }
+
+    bool isMovable() const override {
+        return true;
+    }
+    bool isMovableAcrossScreens() const override {
+        return true;
+    }
+    bool isUserMove() const override {
+        return false;
+    }
+    bool isUserResize() const override {
+        return false;
+    }
+    QRect iconGeometry() const override {
+        return QRect();
+    }
+
+    bool isDesktop() const override {
+        return false;
+    }
+    bool isDock() const override {
+        return false;
+    }
+    bool isToolbar() const override {
+        return false;
+    }
+    bool isMenu() const override {
+        return false;
+    }
+    bool isNormalWindow() const override {
+        return true;
+    }
+    bool isSpecialWindow() const override {
+        return false;
+    }
+    bool isDialog() const override {
+        return false;
+    }
+    bool isSplash() const override {
+        return false;
+    }
+    bool isUtility() const override {
+        return false;
+    }
+    bool isDropdownMenu() const override {
+        return false;
+    }
+    bool isPopupMenu() const override {
+        return false;
+    }
+    bool isTooltip() const override {
+        return false;
+    }
+    bool isNotification() const override {
+        return false;
+    }
+    bool isOnScreenDisplay() const override  {
+        return false;
+    }
+    bool isComboBox() const override {
+        return false;
+    }
+    bool isDNDIcon() const override {
+        return false;
+    }
+    QRect contentsRect() const {
+        return QRect();
+    }
+    bool decorationHasAlpha() const {
+        return false;
+    }
+    QString caption() const {
+        return QString();
+    }
+    QIcon icon() const {
+        return QIcon();
+    }
+    QString windowClass() const {
+        return QString();
+    }
+    QString windowRole() const {
+        return QString();
+    }
+    NET::WindowType windowType() const {
+        return NET::Normal;
+    }
+    bool acceptsFocus() const {
+        return true;
+    }
+    bool keepAbove() const {
+        return false;
+    }
+    bool keepBelow() const {
+        return false;
+    }
+    bool isModal() const {
+        return false;
+    }
+    bool isSkipSwitcher() const {
+        return false;
+    }
+    bool isCurrentTab() const {
+        return true;
+    }
+    bool skipsCloseAnimation() const {
+        return false;
+    }
+    KWayland::Server::SurfaceInterface *surface() const {
+        return nullptr;
+    }
+    bool isFullScreen() const {
+        return false;
+    }
+    bool isUnresponsive() const {
+        return false;
+    }
+
+private:
+    qreal m_opacity = 1.0;
 };
 
 MockEffectWindow::MockEffectWindow(QObject *parent)
@@ -173,9 +330,8 @@
 
 void TestWindowPaintData::testCtor()
 {
-    MockEffectWindowHelper helper;
-    helper.setOpacity(0.5);
-    MockEffectWindow w(&helper);
+    MockEffectWindow w;
+    w.setOpacity(0.5);
     WindowPaintData data(&w);
     QCOMPARE(data.xScale(), 1.0);
     QCOMPARE(data.yScale(), 1.0);
@@ -194,8 +350,7 @@
 
 void TestWindowPaintData::testCopyCtor()
 {
-    MockEffectWindowHelper helper;
-    MockEffectWindow w(&helper);
+    MockEffectWindow w;
     WindowPaintData data(&w);
     WindowPaintData data2(data);
     // no value had been changed
@@ -240,8 +395,7 @@
 
 void TestWindowPaintData::testOperatorMultiplyAssign()
 {
-    MockEffectWindowHelper helper;
-    MockEffectWindow w(&helper);
+    MockEffectWindow w;
     WindowPaintData data(&w);
     // without anything set, it's 1.0 on all axis
     QCOMPARE(data.xScale(), 1.0);
@@ -266,8 +420,7 @@
 
 void TestWindowPaintData::testOperatorPlus()
 {
-    MockEffectWindowHelper helper;
-    MockEffectWindow w(&helper);
+    MockEffectWindow w;
     WindowPaintData data(&w);
     QCOMPARE(data.xTranslation(), 0.0);
     QCOMPARE(data.yTranslation(), 0.0);
@@ -289,8 +442,7 @@
 
 void TestWindowPaintData::testMultiplyBrightness()
 {
-    MockEffectWindowHelper helper;
-    MockEffectWindow w(&helper);
+    MockEffectWindow w;
     WindowPaintData data(&w);
     QCOMPARE(0.2, data.multiplyBrightness(0.2));
     QCOMPARE(0.2, data.brightness());
@@ -303,8 +455,7 @@
 
 void TestWindowPaintData::testMultiplyOpacity()
 {
-    MockEffectWindowHelper helper;
-    MockEffectWindow w(&helper);
+    MockEffectWindow w;
     WindowPaintData data(&w);
     QCOMPARE(0.2, data.multiplyOpacity(0.2));
     QCOMPARE(0.2, data.opacity());
@@ -317,8 +468,7 @@
 
 void TestWindowPaintData::testMultiplySaturation()
 {
-    MockEffectWindowHelper helper;
-    MockEffectWindow w(&helper);
+    MockEffectWindow w;
     WindowPaintData data(&w);
     QCOMPARE(0.2, data.multiplySaturation(0.2));
     QCOMPARE(0.2, data.saturation());
diff --git a/deleted.h b/deleted.h
--- a/deleted.h
+++ b/deleted.h
@@ -37,13 +37,6 @@
     : public Toplevel
 {
     Q_OBJECT
-    Q_PROPERTY(bool minimized READ isMinimized)
-    Q_PROPERTY(bool modal READ isModal)
-    Q_PROPERTY(bool fullScreen READ isFullScreen CONSTANT)
-    Q_PROPERTY(bool isCurrentTab READ isCurrentTab)
-    Q_PROPERTY(bool keepAbove READ keepAbove CONSTANT)
-    Q_PROPERTY(bool keepBelow READ keepBelow CONSTANT)
-    Q_PROPERTY(QString caption READ caption CONSTANT)
 public:
     static Deleted* create(Toplevel* c);
     // used by effects to keep the window around for e.g. fadeout effects when it's destroyed
@@ -68,10 +61,10 @@
     virtual Layer layer() const {
         return m_layer;
     }
-    bool isMinimized() const {
+    bool isMinimized() const override {
         return m_minimized;
     }
-    bool isModal() const {
+    bool isModal() const override {
         return m_modal;
     }
     QList<AbstractClient*> mainClients() const {
@@ -88,20 +81,20 @@
         return m_decorationRenderer;
     }
 
-    bool isFullScreen() const {
+    bool isFullScreen() const override {
         return m_fullscreen;
     }
 
-    bool isCurrentTab() const {
+    bool isCurrentTab() const override {
         return m_wasCurrentTab;
     }
-    bool keepAbove() const {
+    bool keepAbove() const override {
         return m_keepAbove;
     }
-    bool keepBelow() const {
+    bool keepBelow() const override {
         return m_keepBelow;
     }
-    QString caption() const {
+    QString caption() const override {
         return m_caption;
     }
 
diff --git a/effects.h b/effects.h
--- a/effects.h
+++ b/effects.h
@@ -355,18 +355,84 @@
     Q_OBJECT
 public:
     explicit EffectWindowImpl(Toplevel *toplevel);
-    virtual ~EffectWindowImpl();
+    virtual ~EffectWindowImpl() override;
 
     void enablePainting(int reason) override;
     void disablePainting(int reason) override;
     bool isPaintingEnabled() override;
 
     void refWindow() override;
     void unrefWindow() override;
 
-    const EffectWindowGroup* group() const override;
+    bool isDeleted() const override;
+    bool isMinimized() const override;
+    double opacity() const override;
+    bool hasAlpha() const override;
+
+    QStringList activities() const override;
+    int desktop() const override;
+    int x() const override;
+    int y() const override;
+    int width() const override;
+    int height() const override;
+
+    QSize basicUnit() const override;
+    QRect geometry() const override;
+
+    QString caption() const override;
 
+    QRect expandedGeometry() const override;
     QRegion shape() const override;
+    int screen() const override;
+    bool hasOwnShape() const override; // only for shadow effect, for now
+    QPoint pos() const override;
+    QSize size() const override;
+    QRect rect() const override;
+
+    bool isMovable() const override;
+    bool isMovableAcrossScreens() const override;
+    bool isUserMove() const override;
+    bool isUserResize() const override;
+    QRect iconGeometry() const override;
+
+    bool isDesktop() const override;
+    bool isDock() const override;
+    bool isToolbar() const override;
+    bool isMenu() const override;
+    bool isNormalWindow() const override;
+    bool isSpecialWindow() const override;
+    bool isDialog() const override;
+    bool isSplash() const override;
+    bool isUtility() const override;
+    bool isDropdownMenu() const override;
+    bool isPopupMenu() const override;
+    bool isTooltip() const override;
+    bool isNotification() const override;
+    bool isOnScreenDisplay() const override;
+    bool isComboBox() const override;
+    bool isDNDIcon() const override;
+    bool skipsCloseAnimation() const override;
+
+    bool acceptsFocus() const override;
+    bool keepAbove() const override;
+    bool keepBelow() const override;
+    bool isModal() const override;
+
+    KWayland::Server::SurfaceInterface *surface() const override;
+    bool isFullScreen() const override;
+    bool isUnresponsive() const override;
+
+    QRect contentsRect() const override;
+    bool decorationHasAlpha() const override;
+    QIcon icon() const override;
+    QString windowClass() const override;
+    NET::WindowType windowType() const override;
+    bool isSkipSwitcher() const override;
+    bool isCurrentTab() const override;
+    QString windowRole() const override;
+
+    const EffectWindowGroup* group() const override;
+
     QRect decorationInnerRect() const override;
     QByteArray readProperty(long atom, long type, int format) const override;
     void deleteProperty(long atom) const override;
@@ -389,8 +455,8 @@
 
     void elevate(bool elevate);
 
-    void setData(int role, const QVariant &data);
-    QVariant data(int role) const;
+    void setData(int role, const QVariant &data) override;
+    QVariant data(int role) const override;
 
     void registerThumbnail(AbstractThumbnailItem *item);
     QHash<WindowThumbnailItem*, QWeakPointer<EffectWindowImpl> > const &thumbnails() const {
@@ -435,16 +501,16 @@
     void render(QRegion region = infiniteRegion(), double opacity = 1.0, double frameOpacity = 1.0) override;
     Qt::Alignment alignment() const override;
     void setAlignment(Qt::Alignment alignment) override;
-    const QFont& font() const override;
+    const QFont font() const override;
     void setFont(const QFont& font) override;
-    const QRect& geometry() const override;
+    const QRect geometry() const override;
     void setGeometry(const QRect& geometry, bool force = false) override;
-    const QIcon& icon() const override;
+    const QIcon icon() const override;
     void setIcon(const QIcon& icon) override;
-    const QSize& iconSize() const override;
+    const QSize iconSize() const override;
     void setIconSize(const QSize& size) override;
     void setPosition(const QPoint& point) override;
-    const QString& text() const override;
+    const QString text() const override;
     void setText(const QString& text) override;
     EffectFrameStyle style() const override {
         return m_style;
diff --git a/effects.cpp b/effects.cpp
--- a/effects.cpp
+++ b/effects.cpp
@@ -1667,7 +1667,7 @@
 {
     if (Client* c = dynamic_cast< Client* >(toplevel))
         return c->group()->effectGroup();
-    return NULL; // TODO
+    return nullptr; // TODO
 }
 
 void EffectWindowImpl::refWindow()
@@ -1684,6 +1684,100 @@
     abort(); // TODO
 }
 
+#define WINDOW_HELPER( rettype, prototype, toplevelPrototype) \
+    rettype EffectWindowImpl::prototype ( ) const \
+    { \
+        return toplevel->toplevelPrototype(); \
+    }
+
+WINDOW_HELPER(double, opacity, opacity)
+WINDOW_HELPER(bool, hasAlpha, hasAlpha)
+WINDOW_HELPER(int, x, x)
+WINDOW_HELPER(int, y, y)
+WINDOW_HELPER(int, width, width)
+WINDOW_HELPER(int, height, height)
+WINDOW_HELPER(QPoint, pos, pos)
+WINDOW_HELPER(QSize, size, size)
+WINDOW_HELPER(int, screen, screen)
+WINDOW_HELPER(QRect, geometry, geometry)
+WINDOW_HELPER(QRect, expandedGeometry, visibleRect)
+WINDOW_HELPER(QRect, rect, rect)
+WINDOW_HELPER(int, desktop, desktop)
+WINDOW_HELPER(bool, isDesktop, isDesktop)
+WINDOW_HELPER(bool, isDock, isDock)
+WINDOW_HELPER(bool, isToolbar, isToolbar)
+WINDOW_HELPER(bool, isMenu, isMenu)
+WINDOW_HELPER(bool, isNormalWindow, isNormalWindow)
+WINDOW_HELPER(bool, isDialog, isDialog)
+WINDOW_HELPER(bool, isSplash, isSplash)
+WINDOW_HELPER(bool, isUtility, isUtility)
+WINDOW_HELPER(bool, isDropdownMenu, isDropdownMenu)
+WINDOW_HELPER(bool, isPopupMenu, isPopupMenu)
+WINDOW_HELPER(bool, isTooltip, isTooltip)
+WINDOW_HELPER(bool, isNotification, isNotification)
+WINDOW_HELPER(bool, isOnScreenDisplay, isOnScreenDisplay)
+WINDOW_HELPER(bool, isComboBox, isComboBox)
+WINDOW_HELPER(bool, isDNDIcon, isDNDIcon)
+WINDOW_HELPER(bool, isDeleted, isDeleted)
+WINDOW_HELPER(bool, hasOwnShape, shape)
+WINDOW_HELPER(QString, windowRole, windowRole)
+WINDOW_HELPER(QStringList, activities, activities)
+WINDOW_HELPER(bool, skipsCloseAnimation, skipsCloseAnimation)
+WINDOW_HELPER(KWayland::Server::SurfaceInterface *, surface, surface)
+WINDOW_HELPER(QString, caption, caption);
+WINDOW_HELPER(bool, isMinimized, isMinimized)
+WINDOW_HELPER(bool, keepAbove, keepAbove)
+WINDOW_HELPER(bool, keepBelow, keepBelow)
+WINDOW_HELPER(bool, isModal, isModal)
+WINDOW_HELPER(bool, isFullScreen, isFullScreen)
+WINDOW_HELPER(bool, isCurrentTab, isCurrentTab)
+
+//windowClass
+QString EffectWindowImpl::windowClass() const
+{
+    return toplevel->resourceName() + QLatin1Char(' ') + toplevel->resourceClass();
+}
+
+QRect EffectWindowImpl::contentsRect() const
+{
+    return QRect(toplevel->clientPos(), toplevel->clientSize());
+}
+
+NET::WindowType EffectWindowImpl::windowType() const
+{
+    return toplevel->windowType();
+}
+
+#define WINDOW_HELPER_DEFAULT( rettype, prototype, propertyname, defaultValue ) \
+    rettype EffectWindowImpl::prototype ( ) const \
+    { \
+        auto client = qobject_cast<AbstractClient*>(toplevel); \
+        if (!client) { \
+            return defaultValue; \
+        } \
+        return client->propertyname(); \
+    }
+
+WINDOW_HELPER_DEFAULT(bool, isMovable, isMovable, false)
+WINDOW_HELPER_DEFAULT(bool, isMovableAcrossScreens, isMovableAcrossScreens, false)
+WINDOW_HELPER_DEFAULT(bool, isUserMove, isMove, false)
+WINDOW_HELPER_DEFAULT(bool, isUserResize, isResize, false)
+WINDOW_HELPER_DEFAULT(QRect, iconGeometry, iconGeometry, QRect())
+WINDOW_HELPER_DEFAULT(bool, isSpecialWindow, isSpecialWindow, true)
+WINDOW_HELPER_DEFAULT(bool, acceptsFocus, wantsInput, true) // We don't actually know...
+WINDOW_HELPER_DEFAULT(QIcon, icon, icon, QIcon())
+WINDOW_HELPER_DEFAULT(bool, isSkipSwitcher, skipSwitcher, false)
+WINDOW_HELPER_DEFAULT(bool, decorationHasAlpha, decorationHasAlpha, false)
+WINDOW_HELPER_DEFAULT(bool, isUnresponsive, unresponsive, false)
+
+QSize EffectWindowImpl::basicUnit() const
+{
+    if (auto client = qobject_cast<Client*>(toplevel)){
+        return client->basicUnit();
+    }
+    return QSize(1,1);
+}
+
 void EffectWindowImpl::setWindow(Toplevel* w)
 {
     toplevel = w;
@@ -1893,7 +1987,7 @@
     delete m_sceneFrame;
 }
 
-const QFont& EffectFrameImpl::font() const
+const QFont EffectFrameImpl::font() const
 {
     return m_font;
 }
@@ -1919,7 +2013,7 @@
     m_sceneFrame->free();
 }
 
-const QRect& EffectFrameImpl::geometry() const
+const QRect EffectFrameImpl::geometry() const
 {
     return m_geometry;
 }
@@ -1946,7 +2040,7 @@
     free();
 }
 
-const QIcon& EffectFrameImpl::icon() const
+const QIcon EffectFrameImpl::icon() const
 {
     return m_icon;
 }
@@ -1963,7 +2057,7 @@
     m_sceneFrame->freeIconFrame();
 }
 
-const QSize& EffectFrameImpl::iconSize() const
+const QSize EffectFrameImpl::iconSize() const
 {
     return m_iconSize;
 }
@@ -2039,7 +2133,7 @@
     setGeometry(geometry);
 }
 
-const QString& EffectFrameImpl::text() const
+const QString EffectFrameImpl::text() const
 {
     return m_text;
 }
diff --git a/libkwineffects/kwineffects.h b/libkwineffects/kwineffects.h
--- a/libkwineffects/kwineffects.h
+++ b/libkwineffects/kwineffects.h
@@ -2057,188 +2057,189 @@
 
     virtual void refWindow() = 0;
     virtual void unrefWindow() = 0;
-    bool isDeleted() const;
 
-    bool isMinimized() const;
-    double opacity() const;
-    bool hasAlpha() const;
+    virtual bool isDeleted() const = 0;
+
+    virtual bool isMinimized() const = 0;
+    virtual double opacity() const = 0;
+    virtual bool hasAlpha() const = 0;
 
     bool isOnCurrentActivity() const;
     Q_SCRIPTABLE bool isOnActivity(QString id) const;
     bool isOnAllActivities() const;
-    QStringList activities() const;
+    virtual QStringList activities() const = 0;
 
     Q_SCRIPTABLE bool isOnDesktop(int d) const;
     bool isOnCurrentDesktop() const;
     bool isOnAllDesktops() const;
-    int desktop() const; // prefer isOnXXX()
+    virtual int desktop() const = 0; // prefer isOnXXX()
 
-    int x() const;
-    int y() const;
-    int width() const;
-    int height() const;
+    virtual int x() const = 0;
+    virtual int y() const = 0;
+    virtual int width() const = 0;
+    virtual int height() const = 0;
     /**
      * By how much the window wishes to grow/shrink at least. Usually QSize(1,1).
      * MAY BE DISOBEYED BY THE WM! It's only for information, do NOT rely on it at all.
      */
-    QSize basicUnit() const;
-    QRect geometry() const;
+    virtual QSize basicUnit() const = 0;
+    virtual QRect geometry() const = 0;
     /**
      * Geometry of the window including decoration and potentially shadows.
      * May be different from geometry() if the window has a shadow.
      * @since 4.9
      */
-    QRect expandedGeometry() const;
+    virtual QRect expandedGeometry() const = 0;
     virtual QRegion shape() const = 0;
-    int screen() const;
+    virtual int screen() const = 0;
     /** @internal Do not use */
-    bool hasOwnShape() const; // only for shadow effect, for now
-    QPoint pos() const;
-    QSize size() const;
-    QRect rect() const;
-    bool isMovable() const;
-    bool isMovableAcrossScreens() const;
-    bool isUserMove() const;
-    bool isUserResize() const;
-    QRect iconGeometry() const;
+    virtual bool hasOwnShape() const = 0; // only for shadow effect, for now
+    virtual QPoint pos() const = 0;
+    virtual QSize size() const = 0;
+    virtual QRect rect() const = 0;
+    virtual bool isMovable() const = 0;
+    virtual bool isMovableAcrossScreens() const = 0;
+    virtual bool isUserMove() const = 0;
+    virtual bool isUserResize() const = 0;
+    virtual QRect iconGeometry() const = 0;
 
     /**
      * Geometry of the actual window contents inside the whole (including decorations) window.
      */
-    QRect contentsRect() const;
+    virtual QRect contentsRect() const = 0;
     /**
      * Geometry of the transparent rect in the decoration.
      * May be different from contentsRect() if the decoration is extended into the client area.
      * @since 4.5
      */
     virtual QRect decorationInnerRect() const = 0;
     bool hasDecoration() const;
-    bool decorationHasAlpha() const;
+    virtual bool decorationHasAlpha() const = 0;
     virtual QByteArray readProperty(long atom, long type, int format) const = 0;
     virtual void deleteProperty(long atom) const = 0;
 
-    QString caption() const;
-    QIcon icon() const;
-    QString windowClass() const;
-    QString windowRole() const;
+    virtual QString caption() const = 0;
+    virtual QIcon icon() const = 0;
+    virtual QString windowClass() const = 0;
+    virtual QString windowRole() const = 0;
     virtual const EffectWindowGroup* group() const = 0;
 
     /**
      * Returns whether the window is a desktop background window (the one with wallpaper).
      * See _NET_WM_WINDOW_TYPE_DESKTOP at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isDesktop() const;
+    virtual bool isDesktop() const = 0;
     /**
      * Returns whether the window is a dock (i.e. a panel).
      * See _NET_WM_WINDOW_TYPE_DOCK at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isDock() const;
+    virtual bool isDock() const = 0;
     /**
      * Returns whether the window is a standalone (detached) toolbar window.
      * See _NET_WM_WINDOW_TYPE_TOOLBAR at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isToolbar() const;
+    virtual bool isToolbar() const = 0;
     /**
      * Returns whether the window is a torn-off menu.
      * See _NET_WM_WINDOW_TYPE_MENU at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isMenu() const;
+    virtual bool isMenu() const = 0;
     /**
      * Returns whether the window is a "normal" window, i.e. an application or any other window
      * for which none of the specialized window types fit.
      * See _NET_WM_WINDOW_TYPE_NORMAL at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isNormalWindow() const; // normal as in 'NET::Normal or NET::Unknown non-transient'
+    virtual bool isNormalWindow() const = 0; // normal as in 'NET::Normal or NET::Unknown non-transient'
     /**
      * Returns whether the window is any of special windows types (desktop, dock, splash, ...),
      * i.e. window types that usually don't have a window frame and the user does not use window
      * management (moving, raising,...) on them.
      */
-    bool isSpecialWindow() const;
+    virtual bool isSpecialWindow() const = 0;
     /**
      * Returns whether the window is a dialog window.
      * See _NET_WM_WINDOW_TYPE_DIALOG at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isDialog() const;
+    virtual bool isDialog() const = 0;
     /**
      * Returns whether the window is a splashscreen. Note that many (especially older) applications
      * do not support marking their splash windows with this type.
      * See _NET_WM_WINDOW_TYPE_SPLASH at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isSplash() const;
+    virtual bool isSplash() const = 0;
     /**
      * Returns whether the window is a utility window, such as a tool window.
      * See _NET_WM_WINDOW_TYPE_UTILITY at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isUtility() const;
+    virtual bool isUtility() const = 0;
     /**
      * Returns whether the window is a dropdown menu (i.e. a popup directly or indirectly open
      * from the applications menubar).
      * See _NET_WM_WINDOW_TYPE_DROPDOWN_MENU at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isDropdownMenu() const;
+    virtual bool isDropdownMenu() const = 0;
     /**
      * Returns whether the window is a popup menu (that is not a torn-off or dropdown menu).
      * See _NET_WM_WINDOW_TYPE_POPUP_MENU at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isPopupMenu() const; // a context popup, not dropdown, not torn-off
+    virtual bool isPopupMenu() const = 0; // a context popup, not dropdown, not torn-off
     /**
      * Returns whether the window is a tooltip.
      * See _NET_WM_WINDOW_TYPE_TOOLTIP at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isTooltip() const;
+    virtual bool isTooltip() const = 0;
     /**
      * Returns whether the window is a window with a notification.
      * See _NET_WM_WINDOW_TYPE_NOTIFICATION at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isNotification() const;
+    virtual bool isNotification() const = 0;
     /**
      * Returns whether the window is an on screen display window
      * using the non-standard _KDE_NET_WM_WINDOW_TYPE_ON_SCREEN_DISPLAY
      */
-    bool isOnScreenDisplay() const;
+    virtual bool isOnScreenDisplay() const = 0;
     /**
      * Returns whether the window is a combobox popup.
      * See _NET_WM_WINDOW_TYPE_COMBO at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isComboBox() const;
+    virtual bool isComboBox() const = 0;
     /**
      * Returns whether the window is a Drag&Drop icon.
      * See _NET_WM_WINDOW_TYPE_DND at http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    bool isDNDIcon() const;
+    virtual bool isDNDIcon() const = 0;
     /**
      * Returns the NETWM window type
      * See http://standards.freedesktop.org/wm-spec/wm-spec-latest.html .
      */
-    NET::WindowType windowType() const;
+    virtual NET::WindowType windowType() const = 0;
     /**
      * Returns whether the window is managed by KWin (it has control over its placement and other
      * aspects, as opposed to override-redirect windows that are entirely handled by the application).
      */
     bool isManaged() const; // whether it's managed or override-redirect
     /**
      * Returns whether or not the window can accept keyboard focus.
      */
-    bool acceptsFocus() const;
+    virtual bool acceptsFocus() const = 0;
     /**
      * Returns whether or not the window is kept above all other windows.
      */
-    bool keepAbove() const;
+    virtual bool keepAbove() const = 0;
     /**
      * Returns whether the window is kept below all other windows.
      */
-    bool keepBelow() const;
+    virtual bool keepBelow() const = 0;
 
-    bool isModal() const;
+    virtual bool isModal() const = 0;
     Q_SCRIPTABLE virtual KWin::EffectWindow* findModal() = 0;
     Q_SCRIPTABLE virtual QList<KWin::EffectWindow*> mainWindows() const = 0;
 
     /**
     * Returns whether the window should be excluded from window switching effects.
     * @since 4.5
     */
-    bool isSkipSwitcher() const;
+    virtual bool isSkipSwitcher() const = 0;
 
     /**
      * Returns the unmodified window quad list. Can also be used to force rebuilding.
@@ -2250,7 +2251,7 @@
     void unminimize();
     Q_SCRIPTABLE void closeWindow() const;
 
-    bool isCurrentTab() const;
+    virtual bool isCurrentTab() const = 0;
 
     /**
      * @since 4.11
@@ -2260,22 +2261,22 @@
     /**
      * @since 5.0
      **/
-    bool skipsCloseAnimation() const;
+    virtual bool skipsCloseAnimation() const = 0;
 
     /**
      * @since 5.5
      */
-    KWayland::Server::SurfaceInterface *surface() const;
+    virtual KWayland::Server::SurfaceInterface *surface() const = 0;
 
     /**
      * @since 5.6
      **/
-    bool isFullScreen() const;
+    virtual bool isFullScreen() const = 0;
 
     /**
      * @since 5.10
      */
-    bool isUnresponsive() const;
+    virtual bool isUnresponsive() const = 0;
 
     /**
      * @since 5.15
@@ -3277,19 +3278,19 @@
     virtual void setAlignment(Qt::Alignment alignment) = 0;
     virtual Qt::Alignment alignment() const = 0;
     virtual void setGeometry(const QRect& geometry, bool force = false) = 0;
-    virtual const QRect& geometry() const = 0;
+    virtual const QRect geometry() const = 0;
 
     virtual void setText(const QString& text) = 0;
-    virtual const QString& text() const = 0;
+    virtual const QString text() const = 0;
     virtual void setFont(const QFont& font) = 0;
-    virtual const QFont& font() const = 0;
+    virtual const QFont font() const = 0;
     /**
      * Set the icon that will appear on the left-hand size of the frame.
      */
     virtual void setIcon(const QIcon& icon) = 0;
-    virtual const QIcon& icon() const = 0;
+    virtual const QIcon icon() const = 0;
     virtual void setIconSize(const QSize& size) = 0;
-    virtual const QSize& iconSize() const = 0;
+    virtual const QSize iconSize() const = 0;
 
     /**
      * Sets the geometry of a selection.
diff --git a/libkwineffects/kwineffects.cpp b/libkwineffects/kwineffects.cpp
--- a/libkwineffects/kwineffects.cpp
+++ b/libkwineffects/kwineffects.cpp
@@ -808,107 +808,17 @@
 {
 }
 
-#define WINDOW_HELPER( rettype, prototype, propertyname ) \
-    rettype EffectWindow::prototype ( ) const \
-    { \
-        return parent()->property( propertyname ).value< rettype >(); \
-    }
-
-WINDOW_HELPER(double, opacity, "opacity")
-WINDOW_HELPER(bool, hasAlpha, "alpha")
-WINDOW_HELPER(int, x, "x")
-WINDOW_HELPER(int, y, "y")
-WINDOW_HELPER(int, width, "width")
-WINDOW_HELPER(int, height, "height")
-WINDOW_HELPER(QPoint, pos, "pos")
-WINDOW_HELPER(QSize, size, "size")
-WINDOW_HELPER(int, screen, "screen")
-WINDOW_HELPER(QRect, geometry, "geometry")
-WINDOW_HELPER(QRect, expandedGeometry, "visibleRect")
-WINDOW_HELPER(QRect, rect, "rect")
-WINDOW_HELPER(int, desktop, "desktop")
-WINDOW_HELPER(bool, isDesktop, "desktopWindow")
-WINDOW_HELPER(bool, isDock, "dock")
-WINDOW_HELPER(bool, isToolbar, "toolbar")
-WINDOW_HELPER(bool, isMenu, "menu")
-WINDOW_HELPER(bool, isNormalWindow, "normalWindow")
-WINDOW_HELPER(bool, isDialog, "dialog")
-WINDOW_HELPER(bool, isSplash, "splash")
-WINDOW_HELPER(bool, isUtility, "utility")
-WINDOW_HELPER(bool, isDropdownMenu, "dropdownMenu")
-WINDOW_HELPER(bool, isPopupMenu, "popupMenu")
-WINDOW_HELPER(bool, isTooltip, "tooltip")
-WINDOW_HELPER(bool, isNotification, "notification")
-WINDOW_HELPER(bool, isOnScreenDisplay, "onScreenDisplay")
-WINDOW_HELPER(bool, isComboBox, "comboBox")
-WINDOW_HELPER(bool, isDNDIcon, "dndIcon")
-WINDOW_HELPER(bool, isDeleted, "deleted")
-WINDOW_HELPER(bool, hasOwnShape, "shaped")
-WINDOW_HELPER(QString, windowRole, "windowRole")
-WINDOW_HELPER(QStringList, activities, "activities")
-WINDOW_HELPER(bool, skipsCloseAnimation, "skipsCloseAnimation")
-WINDOW_HELPER(KWayland::Server::SurfaceInterface *, surface, "surface")
-
-QString EffectWindow::windowClass() const
-{
-    return parent()->property("resourceName").toString() + QLatin1Char(' ') + parent()->property("resourceClass").toString();
-}
-
-QRect EffectWindow::contentsRect() const
-{
-    return QRect(parent()->property("clientPos").toPoint(), parent()->property("clientSize").toSize());
-}
-
-NET::WindowType EffectWindow::windowType() const
-{
-    return static_cast<NET::WindowType>(parent()->property("windowType").toInt());
-}
-
 bool EffectWindow::isOnActivity(QString activity) const
 {
-    const QStringList activities = parent()->property("activities").toStringList();
-    return activities.isEmpty() || activities.contains(activity);
+    const QStringList _activities = activities();
+    return _activities.isEmpty() || _activities.contains(activity);
 }
 
 bool EffectWindow::isOnAllActivities() const
 {
-    return parent()->property("activities").toStringList().isEmpty();
+    return activities().isEmpty();
 }
 
-#undef WINDOW_HELPER
-
-#define WINDOW_HELPER_DEFAULT( rettype, prototype, propertyname, defaultValue ) \
-    rettype EffectWindow::prototype ( ) const \
-    { \
-        const QVariant variant = parent()->property( propertyname ); \
-        if (!variant.isValid()) { \
-            return defaultValue; \
-        } \
-        return variant.value< rettype >(); \
-    }
-
-WINDOW_HELPER_DEFAULT(bool, isMinimized, "minimized", false)
-WINDOW_HELPER_DEFAULT(bool, isMovable, "moveable", false)
-WINDOW_HELPER_DEFAULT(bool, isMovableAcrossScreens, "moveableAcrossScreens", false)
-WINDOW_HELPER_DEFAULT(QString, caption, "caption", QString())
-WINDOW_HELPER_DEFAULT(bool, keepAbove, "keepAbove", true)
-WINDOW_HELPER_DEFAULT(bool, keepBelow, "keepBelow", false)
-WINDOW_HELPER_DEFAULT(bool, isModal, "modal", false)
-WINDOW_HELPER_DEFAULT(QSize, basicUnit, "basicUnit", QSize(1, 1))
-WINDOW_HELPER_DEFAULT(bool, isUserMove, "move", false)
-WINDOW_HELPER_DEFAULT(bool, isUserResize, "resize", false)
-WINDOW_HELPER_DEFAULT(QRect, iconGeometry, "iconGeometry", QRect())
-WINDOW_HELPER_DEFAULT(bool, isSpecialWindow, "specialWindow", true)
-WINDOW_HELPER_DEFAULT(bool, acceptsFocus, "wantsInput", true) // We don't actually know...
-WINDOW_HELPER_DEFAULT(QIcon, icon, "icon", QIcon())
-WINDOW_HELPER_DEFAULT(bool, isSkipSwitcher, "skipSwitcher", false)
-WINDOW_HELPER_DEFAULT(bool, isCurrentTab, "isCurrentTab", true)
-WINDOW_HELPER_DEFAULT(bool, decorationHasAlpha, "decorationHasAlpha", false)
-WINDOW_HELPER_DEFAULT(bool, isFullScreen, "fullScreen", false)
-WINDOW_HELPER_DEFAULT(bool, isUnresponsive, "unresponsive", false)
-
-#undef WINDOW_HELPER_DEFAULT
-
 #define WINDOW_HELPER_SETTER( prototype, propertyname, args, value ) \
     void EffectWindow::prototype ( args ) \
     {\
diff --git a/toplevel.h b/toplevel.h
--- a/toplevel.h
+++ b/toplevel.h
@@ -457,6 +457,26 @@
      **/
     virtual bool isPopupWindow() const;
 
+    /**
+     * @returns The caption consisting of @link{captionNormal} and @link{captionSuffix}
+     * @see captionNormal
+     * @see captionSuffix
+    **/
+    virtual QString caption() const;
+
+    virtual bool isMinimized() const;
+    virtual bool isModal() const;
+    virtual bool isFullScreen() const;
+    virtual bool keepAbove() const;
+    virtual bool keepBelow() const;
+    /*
+    *   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
+    *   client, this function stops it.
+    */
+    virtual bool isCurrentTab() const;
+
+
 Q_SIGNALS:
     void opacityChanged(KWin::Toplevel* toplevel, qreal oldOpacity);
     void damaged(KWin::Toplevel* toplevel, const QRect& damage);
@@ -466,6 +486,7 @@
     void windowClosed(KWin::Toplevel* toplevel, KWin::Deleted* deleted);
     void windowShown(KWin::Toplevel* toplevel);
     void windowHidden(KWin::Toplevel* toplevel);
+    void captionChanged();
     /**
      * Signal emitted when the window's shape state changed. That is if it did not have a shape
      * and received one or if the shape was withdrawn. Think of Chromium enabling/disabling KWin's
diff --git a/toplevel.cpp b/toplevel.cpp
--- a/toplevel.cpp
+++ b/toplevel.cpp
@@ -553,5 +553,41 @@
     return geometry();
 }
 
+QString Toplevel::caption() const
+{
+    return QString();
+}
+
+bool Toplevel::isMinimized() const
+{
+    return false;
+}
+
+bool Toplevel::isModal() const
+{
+    return false;
+}
+
+bool Toplevel::isCurrentTab() const
+{
+    return false;
+}
+
+bool Toplevel::isFullScreen() const
+{
+    return false;
+}
+
+bool Toplevel::keepAbove() const
+{
+    return false;
+}
+
+bool Toplevel::keepBelow() const
+{
+    return false;
+}
+
+
 } // namespace