diff --git a/shell/panelview.cpp b/shell/panelview.cpp
--- a/shell/panelview.cpp
+++ b/shell/panelview.cpp
@@ -951,19 +951,33 @@
 
 void PanelView::updateMask()
 {
-    if (KWindowSystem::compositingActive()) {
-        setMask(QRegion());
-    } else {
+    QRegion mask;
+
+    QQuickItem *rootObject = this->rootObject();
+    if (rootObject) {
+        const QVariant maskProperty = rootObject->property("panelMask");
+        if (static_cast<QMetaType::Type>(maskProperty.type()) == QMetaType::QRegion) {
+            mask = maskProperty.value<QRegion>();
+        }
+    }
+
+    // old hack for non-compositing:
+    // assuming the desktoptheme uses "widgets/panel-background" for the panel
+    // before "panelMask" was added to expected property set of panel objects
+    // TODO: understand if still needed
+    if (mask.isEmpty() && !KWindowSystem::compositingActive()) {
         if (!m_background) {
             m_background = new Plasma::FrameSvg(this);
             m_background->setImagePath(QStringLiteral("widgets/panel-background"));
         }
 
         m_background->setEnabledBorders(enabledBorders());
 
         m_background->resizeFrame(size());
-        setMask(m_background->mask());
+        mask = m_background->mask();
     }
+
+    setMask(mask);
 }
 
 bool PanelView::canSetStrut() const