diff --git a/abstract_client.h b/abstract_client.h
--- a/abstract_client.h
+++ b/abstract_client.h
@@ -1176,6 +1176,7 @@
     void setDecoration(KDecoration2::Decoration *decoration) {
         m_decoration.decoration = decoration;
     }
+    virtual void createDecoration(const QRect &oldGeometry);
     virtual void destroyDecoration();
     void startDecorationDoubleClickTimer();
     void invalidateDecorationDoubleClickTimer();
diff --git a/abstract_client.cpp b/abstract_client.cpp
--- a/abstract_client.cpp
+++ b/abstract_client.cpp
@@ -2137,6 +2137,27 @@
     updateCursor();
 }
 
+void AbstractClient::createDecoration(const QRect &oldGeometry)
+{
+    KDecoration2::Decoration *decoration = Decoration::DecorationBridge::self()->createDecoration(this);
+    if (decoration) {
+        QMetaObject::invokeMethod(decoration, "update", Qt::QueuedConnection);
+        connect(decoration, &KDecoration2::Decoration::shadowChanged, this, &Toplevel::updateShadow);
+        connect(decoration, &KDecoration2::Decoration::bordersChanged, this, [this]() {
+            GeometryUpdatesBlocker blocker(this);
+            const QRect oldGeometry = frameGeometry();
+            if (!isShade()) {
+                checkWorkspacePosition(oldGeometry);
+            }
+            emit geometryShapeChanged(this, oldGeometry);
+        });
+    }
+    setDecoration(decoration);
+    setFrameGeometry(QRect(oldGeometry.topLeft(), clientSizeToFrameSize(clientSize())));
+
+    emit geometryShapeChanged(this, oldGeometry);
+}
+
 void AbstractClient::destroyDecoration()
 {
     delete m_decoration.decoration;
diff --git a/internal_client.h b/internal_client.h
--- a/internal_client.h
+++ b/internal_client.h
@@ -90,13 +90,11 @@
 protected:
     bool acceptsFocus() const override;
     bool belongsToSameApplication(const AbstractClient *other, SameApplicationChecks checks) const override;
-    void destroyDecoration() override;
     void doMove(int x, int y) override;
     void doResizeSync() override;
     void updateCaption() override;
 
 private:
-    void createDecoration(const QRect &rect);
     void requestGeometry(const QRect &rect);
     void commitGeometry(const QRect &rect);
     void setCaption(const QString &caption);
diff --git a/internal_client.cpp b/internal_client.cpp
--- a/internal_client.cpp
+++ b/internal_client.cpp
@@ -496,17 +496,6 @@
     return qobject_cast<const InternalClient *>(other) != nullptr;
 }
 
-void InternalClient::destroyDecoration()
-{
-    if (!isDecorated()) {
-        return;
-    }
-
-    const QRect clientGeometry = frameRectToClientRect(frameGeometry());
-    AbstractClient::destroyDecoration();
-    setFrameGeometry(clientGeometry);
-}
-
 void InternalClient::doMove(int x, int y)
 {
     Q_UNUSED(x)
@@ -537,32 +526,6 @@
     }
 }
 
-void InternalClient::createDecoration(const QRect &rect)
-{
-    KDecoration2::Decoration *decoration = Decoration::DecorationBridge::self()->createDecoration(this);
-    if (decoration) {
-        QMetaObject::invokeMethod(decoration, "update", Qt::QueuedConnection);
-        connect(decoration, &KDecoration2::Decoration::shadowChanged, this, &Toplevel::updateShadow);
-        connect(decoration, &KDecoration2::Decoration::bordersChanged, this,
-            [this]() {
-                GeometryUpdatesBlocker blocker(this);
-                const QRect oldGeometry = frameGeometry();
-                if (!isShade()) {
-                    checkWorkspacePosition(oldGeometry);
-                }
-                emit geometryShapeChanged(this, oldGeometry);
-            }
-        );
-    }
-
-    const QRect oldFrameGeometry = frameGeometry();
-
-    setDecoration(decoration);
-    setFrameGeometry(clientRectToFrameRect(rect));
-
-    emit geometryShapeChanged(this, oldFrameGeometry);
-}
-
 void InternalClient::requestGeometry(const QRect &rect)
 {
     if (m_internalWindow) {
diff --git a/x11client.h b/x11client.h
--- a/x11client.h
+++ b/x11client.h
@@ -433,7 +433,7 @@
     void grabButton(int mod);
     void ungrabButton(int mod);
     void resizeDecoration();
-    void createDecoration(const QRect &oldgeom);
+    void createDecoration(const QRect &oldgeom) override;
 
     void pingWindow();
     void killProcess(bool ask, xcb_timestamp_t timestamp = XCB_TIME_CURRENT_TIME);
diff --git a/xdgshellclient.h b/xdgshellclient.h
--- a/xdgshellclient.h
+++ b/xdgshellclient.h
@@ -170,7 +170,6 @@
      * At this point all initial properties should have been set by the client.
      */
     void finishInit();
-    void createDecoration(const QRect &oldgeom);
     void createWindowId();
     void updateIcon();
     bool shouldExposeToWindowManagement();
diff --git a/xdgshellclient.cpp b/xdgshellclient.cpp
--- a/xdgshellclient.cpp
+++ b/xdgshellclient.cpp
@@ -460,31 +460,6 @@
     updateShowOnScreenEdge();
 }
 
-void XdgShellClient::createDecoration(const QRect &oldGeom)
-{
-    KDecoration2::Decoration *decoration = Decoration::DecorationBridge::self()->createDecoration(this);
-    if (decoration) {
-        QMetaObject::invokeMethod(decoration, "update", Qt::QueuedConnection);
-        connect(decoration, &KDecoration2::Decoration::shadowChanged, this, &Toplevel::updateShadow);
-        connect(decoration, &KDecoration2::Decoration::bordersChanged, this,
-            [this]() {
-                GeometryUpdatesBlocker blocker(this);
-                RequestGeometryBlocker requestBlocker(this);
-                const QRect oldGeometry = frameGeometry();
-                if (!isShade()) {
-                    checkWorkspacePosition(oldGeometry);
-                }
-                emit geometryShapeChanged(this, oldGeometry);
-            }
-        );
-    }
-    setDecoration(decoration);
-    // TODO: ensure the new geometry still fits into the client area (e.g. maximized windows)
-    doSetGeometry(QRect(oldGeom.topLeft(), m_windowGeometry.size() + QSize(borderLeft() + borderRight(), borderBottom() + borderTop())));
-
-    emit geometryShapeChanged(this, oldGeom);
-}
-
 void XdgShellClient::updateDecoration(bool check_workspace_pos, bool force)
 {
     if (!force &&