diff --git a/autotests/integration/internal_window.cpp b/autotests/integration/internal_window.cpp
--- a/autotests/integration/internal_window.cpp
+++ b/autotests/integration/internal_window.cpp
@@ -61,6 +61,8 @@
     void testMove();
     void testSkipCloseAnimation_data();
     void testSkipCloseAnimation();
+    void testModifierClickUnrestrictedMove();
+    void testModifierScroll();
 };
 
 class HelperWindow : public QRasterWindow
@@ -175,6 +177,7 @@
     kwinApp()->platform()->setInitialWindowSize(QSize(1280, 1024));
     QMetaObject::invokeMethod(kwinApp()->platform(), "setOutputCount", Qt::DirectConnection, Q_ARG(int, 2));
     QVERIFY(waylandServer()->init(s_socketName.toLocal8Bit()));
+    kwinApp()->setConfig(KSharedConfig::openConfig(QString(), KConfig::SimpleConfig));
 
     kwinApp()->start();
     QVERIFY(workspaceCreatedSpy.wait());
@@ -212,6 +215,7 @@
     ShellClient *c = clientAddedSpy.first().first().value<ShellClient*>();
     QVERIFY(c->isInternal());
     QCOMPARE(c->icon().name(), QStringLiteral("wayland"));
+    QVERIFY(!c->isDecorated());
     QCOMPARE(workspace()->findToplevel(&win), c);
     QCOMPARE(c->geometry(), QRect(0, 0, 100, 100));
     QVERIFY(c->isShown(false));
@@ -589,6 +593,84 @@
     QCOMPARE(internalClient->skipsCloseAnimation(), initial);
 }
 
+void InternalWindowTest::testModifierClickUnrestrictedMove()
+{
+    QSignalSpy clientAddedSpy(waylandServer(), &WaylandServer::shellClientAdded);
+    QVERIFY(clientAddedSpy.isValid());
+    HelperWindow win;
+    win.setGeometry(0, 0, 100, 100);
+    win.setFlags(win.flags() & ~Qt::FramelessWindowHint);
+    win.show();
+    QVERIFY(clientAddedSpy.wait());
+    QCOMPARE(clientAddedSpy.count(), 1);
+    auto internalClient = clientAddedSpy.first().first().value<ShellClient*>();
+    QVERIFY(internalClient);
+    QVERIFY(internalClient->isDecorated());
+
+    KConfigGroup group = kwinApp()->config()->group("MouseBindings");
+    group.writeEntry("CommandAllKey", "Alt");
+    group.writeEntry("CommandAll1", "Move");
+    group.writeEntry("CommandAll2", "Move");
+    group.writeEntry("CommandAll3", "Move");
+    group.sync();
+    workspace()->slotReconfigure();
+    QCOMPARE(options->commandAllModifier(), Qt::AltModifier);
+    QCOMPARE(options->commandAll1(), Options::MouseUnrestrictedMove);
+    QCOMPARE(options->commandAll2(), Options::MouseUnrestrictedMove);
+    QCOMPARE(options->commandAll3(), Options::MouseUnrestrictedMove);
+
+    // move cursor on window
+    Cursor::setPos(internalClient->geometry().center());
+
+    // simulate modifier+click
+    quint32 timestamp = 1;
+    kwinApp()->platform()->keyboardKeyPressed(KEY_LEFTALT, timestamp++);
+    QVERIFY(!internalClient->isMove());
+    kwinApp()->platform()->pointerButtonPressed(BTN_LEFT, timestamp++);
+    QVERIFY(internalClient->isMove());
+    // release modifier should not change it
+    kwinApp()->platform()->keyboardKeyReleased(KEY_LEFTALT, timestamp++);
+    QVERIFY(internalClient->isMove());
+    // but releasing the key should end move/resize
+    kwinApp()->platform()->pointerButtonReleased(BTN_LEFT, timestamp++);
+    QVERIFY(!internalClient->isMove());
+}
+
+void InternalWindowTest::testModifierScroll()
+{
+    QSignalSpy clientAddedSpy(waylandServer(), &WaylandServer::shellClientAdded);
+    QVERIFY(clientAddedSpy.isValid());
+    HelperWindow win;
+    win.setGeometry(0, 0, 100, 100);
+    win.setFlags(win.flags() & ~Qt::FramelessWindowHint);
+    win.show();
+    QVERIFY(clientAddedSpy.wait());
+    QCOMPARE(clientAddedSpy.count(), 1);
+    auto internalClient = clientAddedSpy.first().first().value<ShellClient*>();
+    QVERIFY(internalClient);
+    QVERIFY(internalClient->isDecorated());
+
+    KConfigGroup group = kwinApp()->config()->group("MouseBindings");
+    group.writeEntry("CommandAllKey", "Alt");
+    group.writeEntry("CommandAllWheel", "change opacity");
+    group.sync();
+    workspace()->slotReconfigure();
+
+    // move cursor on window
+    Cursor::setPos(internalClient->geometry().center());
+
+    // set the opacity to 0.5
+    internalClient->setOpacity(0.5);
+    QCOMPARE(internalClient->opacity(), 0.5);
+    quint32 timestamp = 1;
+    kwinApp()->platform()->keyboardKeyPressed(KEY_LEFTALT, timestamp++);
+    kwinApp()->platform()->pointerAxisVertical(-5, timestamp++);
+    QCOMPARE(internalClient->opacity(), 0.6);
+    kwinApp()->platform()->pointerAxisVertical(5, timestamp++);
+    QCOMPARE(internalClient->opacity(), 0.5);
+    kwinApp()->platform()->keyboardKeyReleased(KEY_LEFTALT, timestamp++);
+}
+
 }
 
 WAYLANDTEST_MAIN(KWin::InternalWindowTest)
diff --git a/input.cpp b/input.cpp
--- a/input.cpp
+++ b/input.cpp
@@ -766,6 +766,64 @@
     }
 };
 
+
+namespace {
+
+enum class MouseAction {
+    ModifierOnly,
+    ModifierAndWindow
+};
+std::pair<bool, bool> performClientMouseAction(QMouseEvent *event, AbstractClient *client, MouseAction action = MouseAction::ModifierOnly)
+{
+    Options::MouseCommand command = Options::MouseNothing;
+    bool wasAction = false;
+    if (static_cast<MouseEvent*>(event)->modifiersRelevantForGlobalShortcuts() == options->commandAllModifier()) {
+        wasAction = true;
+        switch (event->button()) {
+        case Qt::LeftButton:
+            command = options->commandAll1();
+            break;
+        case Qt::MiddleButton:
+            command = options->commandAll2();
+            break;
+        case Qt::RightButton:
+            command = options->commandAll3();
+            break;
+        default:
+            // nothing
+            break;
+        }
+    } else {
+        if (action == MouseAction::ModifierAndWindow) {
+            command = client->getMouseCommand(event->button(), &wasAction);
+        }
+    }
+    if (wasAction) {
+        return std::make_pair(wasAction, !client->performMouseCommand(command, event->globalPos()));
+    }
+    return std::make_pair(wasAction, false);
+}
+
+std::pair<bool, bool> performClientWheelAction(QWheelEvent *event, AbstractClient *c, MouseAction action = MouseAction::ModifierOnly)
+{
+    bool wasAction = false;
+    Options::MouseCommand command = Options::MouseNothing;
+    if (static_cast<WheelEvent*>(event)->modifiersRelevantForGlobalShortcuts() == options->commandAllModifier()) {
+        wasAction = true;
+        command = options->operationWindowMouseWheel(-1 * event->angleDelta().y());
+    } else {
+        if (action == MouseAction::ModifierAndWindow) {
+            command = c->getWheelCommand(Qt::Vertical, &wasAction);
+        }
+    }
+    if (wasAction) {
+        return std::make_pair(wasAction, !c->performMouseCommand(command, event->globalPos()));
+    }
+    return std::make_pair(wasAction, false);
+}
+
+}
+
 class InternalWindowEventFilter : public InputEventFilter {
     bool pointerEvent(QMouseEvent *event, quint32 nativeButton) override {
         Q_UNUSED(nativeButton)
@@ -780,6 +838,24 @@
         if (!internal) {
             return false;
         }
+        // find client
+        switch (event->type())
+        {
+        case QEvent::MouseButtonPress:
+        case QEvent::MouseButtonRelease: {
+            auto s = waylandServer()->findClient(internal);
+            if (s && s->isDecorated()) {
+                // only perform mouse commands on decorated internal windows
+                const auto actionResult = performClientMouseAction(event, s);
+                if (actionResult.first) {
+                    return actionResult.second;
+                }
+            }
+            break;
+        }
+        default:
+            break;
+        }
         QMouseEvent e(event->type(),
                         event->pos() - internal->position(),
                         event->globalPos(),
@@ -793,6 +869,16 @@
         if (!internal) {
             return false;
         }
+        if (event->angleDelta().y() != 0) {
+            auto s = waylandServer()->findClient(internal);
+            if (s && s->isDecorated()) {
+                // client window action only on vertical scrolling
+                const auto actionResult = performClientWheelAction(event, s);
+                if (actionResult.first) {
+                    return actionResult.second;
+                }
+            }
+        }
         const QPointF localPos = event->globalPosF() - QPointF(internal->x(), internal->y());
         const Qt::Orientation orientation = (event->angleDelta().x() != 0) ? Qt::Horizontal : Qt::Vertical;
         const int delta = event->angleDelta().x() != 0 ? event->angleDelta().x() : event->angleDelta().y();
@@ -929,63 +1015,6 @@
     QPointF m_lastLocalTouchPos;
 };
 
-namespace {
-
-enum class MouseAction {
-    ModifierOnly,
-    ModifierAndWindow
-};
-std::pair<bool, bool> performClientMouseAction(QMouseEvent *event, AbstractClient *client, MouseAction action = MouseAction::ModifierOnly)
-{
-    Options::MouseCommand command = Options::MouseNothing;
-    bool wasAction = false;
-    if (static_cast<MouseEvent*>(event)->modifiersRelevantForGlobalShortcuts() == options->commandAllModifier()) {
-        wasAction = true;
-        switch (event->button()) {
-        case Qt::LeftButton:
-            command = options->commandAll1();
-            break;
-        case Qt::MiddleButton:
-            command = options->commandAll2();
-            break;
-        case Qt::RightButton:
-            command = options->commandAll3();
-            break;
-        default:
-            // nothing
-            break;
-        }
-    } else {
-        if (action == MouseAction::ModifierAndWindow) {
-            command = client->getMouseCommand(event->button(), &wasAction);
-        }
-    }
-    if (wasAction) {
-        return std::make_pair(wasAction, !client->performMouseCommand(command, event->globalPos()));
-    }
-    return std::make_pair(wasAction, false);
-}
-
-std::pair<bool, bool> performClientWheelAction(QWheelEvent *event, AbstractClient *c, MouseAction action = MouseAction::ModifierOnly)
-{
-    bool wasAction = false;
-    Options::MouseCommand command = Options::MouseNothing;
-    if (static_cast<WheelEvent*>(event)->modifiersRelevantForGlobalShortcuts() == options->commandAllModifier()) {
-        wasAction = true;
-        command = options->operationWindowMouseWheel(-1 * event->angleDelta().y());
-    } else {
-        if (action == MouseAction::ModifierAndWindow) {
-            command = c->getWheelCommand(Qt::Vertical, &wasAction);
-        }
-    }
-    if (wasAction) {
-        return std::make_pair(wasAction, !c->performMouseCommand(command, event->globalPos()));
-    }
-    return std::make_pair(wasAction, false);
-}
-
-}
-
 class DecorationEventFilter : public InputEventFilter {
 public:
     bool pointerEvent(QMouseEvent *event, quint32 nativeButton) override {