diff --git a/scene.cpp b/scene.cpp
index 40a39e8fe9..80c687a2df 100644
--- a/scene.cpp
+++ b/scene.cpp
@@ -284,11 +284,17 @@ void Scene::paintSimpleScreen(int orig_mask, const QRegion &region)
             if (!(client && client->decorationHasAlpha())) {
                 data.clip = window->decorationShape().translated(window->pos());
             }
-            data.clip |= window->clientShape().translated(window->pos() + window->bufferOffset());
+            const WindowPixmap *windowPixmap = window->windowPixmap<WindowPixmap>();
+            if (windowPixmap) {
+                data.clip |= windowPixmap->mapToGlobal(windowPixmap->shape());
+            }
         } else if (toplevel->hasAlpha() && toplevel->opacity() == 1.0) {
-            const QRegion clientShape = window->clientShape().translated(window->pos() + window->bufferOffset());
-            const QRegion opaqueShape = toplevel->opaqueRegion().translated(window->pos() + toplevel->clientPos());
-            data.clip = clientShape & opaqueShape;
+            const WindowPixmap *windowPixmap = window->windowPixmap<WindowPixmap>();
+            if (windowPixmap) {
+                const QRegion shape = windowPixmap->mapToGlobal(windowPixmap->shape());
+                const QRegion opaque = windowPixmap->mapToGlobal(windowPixmap->opaque());
+                data.clip = shape & opaque;
+            }
         } else {
             data.clip = QRegion();
         }
@@ -1279,6 +1285,11 @@ QRegion WindowPixmap::shape() const
     return m_window->clientShape();
 }
 
+QRegion WindowPixmap::opaque() const
+{
+    return toplevel()->opaqueRegion().translated(toplevel()->clientPos());
+}
+
 bool WindowPixmap::hasAlphaChannel() const
 {
     if (buffer())
@@ -1298,6 +1309,11 @@ QPointF WindowPixmap::mapToBuffer(const QPointF &point) const
     return point * scale();
 }
 
+QRegion WindowPixmap::mapToGlobal(const QRegion &region) const
+{
+    return region.translated(m_window->pos() + framePosition());
+}
+
 //****************************************
 // Scene::EffectFrame
 //****************************************
diff --git a/scene.h b/scene.h
index af1bdbc67f..729212a7ae 100644
--- a/scene.h
+++ b/scene.h
@@ -357,9 +357,6 @@ public:
         return {};
     }
 
-protected:
-    WindowQuadList makeDecorationQuads(const QRect *rects, const QRegion &region, qreal textureScale = 1.0) const;
-    WindowQuadList makeContentsQuads() const;
     /**
      * @brief Returns the WindowPixmap for this Window.
      *
@@ -377,6 +374,10 @@ protected:
      */
     template<typename T> T *windowPixmap() const;
     template<typename T> T *previousWindowPixmap() const;
+
+protected:
+    WindowQuadList makeDecorationQuads(const QRect *rects, const QRegion &region, qreal textureScale = 1.0) const;
+    WindowQuadList makeContentsQuads() const;
     /**
      * @brief Factory method to create a WindowPixmap.
      *
@@ -497,6 +498,12 @@ public:
      * The upper left corner of the attached buffer corresponds to (0, 0).
      */
     QRegion shape() const;
+    /**
+     * Returns the region that specifies the opaque area inside the attached buffer.
+     *
+     * The upper left corner of the attached buffer corresponds to (0, 0).
+     */
+    QRegion opaque() const;
     /**
      * The geometry of the Client's content inside the pixmap. In case of a decorated Client the
      * pixmap also contains the decoration which is not rendered into this pixmap, though. This
@@ -520,6 +527,10 @@ public:
      * Maps the specified @a point from the window pixmap coordinates to the buffer pixel coordinates.
      */
     QPointF mapToBuffer(const QPointF &point) const;
+    /**
+     * Maps the specified @a region from the window pixmap coordinates to the global screen coordinates.
+     */
+    QRegion mapToGlobal(const QRegion &region) const;
 
     /**
      * @returns the parent WindowPixmap in the sub-surface tree