Wayland: Support classical indicators too

The Indicator Window is top-level, but on Wayland that can't do,
as we have no way to position it. So parent it. The indicators
are now under the window being dragged, but that's no so bad, as it's
smi-transparent, so you still see the indicator.

src/FrameworkWidgetFactory.cpp

@@ -91,12 +91,6 @@ FloatingWindow *DefaultWidgetFactory::createFloatingWindow(Frame *frame, MainWin
 
 DropIndicatorOverlayInterface *DefaultWidgetFactory::createDropIndicatorOverlay(DropArea *dropArea) const
 {
-    if (isWayland() && s_dropIndicatorType == DropIndicatorType::Classic) {
-        qWarning() << Q_FUNC_INFO << "Classical indicators aren't supported on Wayland yet."
-                   << "Falling back to Segmented Indicators";
-        s_dropIndicatorType = DropIndicatorType::Segmented;
-    }
-
     switch (s_dropIndicatorType) {
     case DropIndicatorType::Classic:
         return new ClassicIndicators(dropArea);

src/private/WindowBeingDragged.cpp

@@ -221,7 +221,7 @@ QPixmap WindowBeingDraggedWayland::pixmap() const
 {
     QPixmap pixmap(size());
     QPainter p(&pixmap);
-    p.setOpacity(0.8);
+    p.setOpacity(0.7);
 
     if (m_floatingWindow) {
         m_floatingWindow->render(&p);

src/private/indicators/ClassicIndicators.cpp

@@ -197,7 +197,10 @@ void ClassicIndicators::setDropLocation(ClassicIndicators::DropLocation location
 void ClassicIndicators::updateWindowPosition()
 {
     QRect rect = this->rect();
-    QPoint pos = mapToGlobal(QPoint(0, 0));
-    rect.moveTo(pos);
+    if (m_indicatorWindow->isWindow()) {
+        // On all non-wayland platforms it's a top-level.
+        QPoint pos = mapToGlobal(QPoint(0, 0));
+        rect.moveTo(pos);
+    }
     m_indicatorWindow->setGeometry(rect);
 }

src/private/indicators/ClassicIndicatorsWindow.cpp

@@ -101,8 +101,22 @@ QString Indicator::iconFileName(bool active) const
                                                          : QStringLiteral(":/img/classic_indicators/opaque/%1.png").arg(name);
 }
 
+static QWidgetAdapter* parentForIndicatorWindow(ClassicIndicators *classicIndicators_)
+{
+    // On Wayland it can't be a top-level, as we have no way of positioning it
+
+    return isWayland() ? classicIndicators_
+                       : nullptr;
+}
+
+static Qt::WindowFlags flagsForIndicatorWindow()
+{
+    return isWayland() ? Qt::Widget
+                       : (Qt::Tool | Qt::BypassWindowManagerHint);
+}
+
 IndicatorWindow::IndicatorWindow(ClassicIndicators *classicIndicators_)
-    : QWidget(nullptr, Qt::Tool | Qt::BypassWindowManagerHint)
+    : QWidget(parentForIndicatorWindow(classicIndicators_), flagsForIndicatorWindow())
     , classicIndicators(classicIndicators_)
     , m_center(new Indicator(classicIndicators, this, DropIndicatorOverlayInterface::DropLocation_Center)) // Each indicator is not a top-level. Otherwise there's noticeable delay.
     , m_left(new Indicator(classicIndicators, this, DropIndicatorOverlayInterface::DropLocation_Left))