qtquick: Add "Close All" option in the example

examples/qtquick/dockwidgets/main.qml

@@ -36,6 +36,13 @@ ApplicationWindow {
                 }
             }
 
+            Action {
+                text: qsTr("Close All")
+                onTriggered: {
+                   _kddwDockRegistry.clear();
+                }
+            }
+
             MenuSeparator { }
             Action { text: qsTr("&Quit")
                 onTriggered: {

src/private/DockRegistry_p.h

@@ -137,7 +137,7 @@ public:
      * This is called before restoring a layout.
      * @param affinities if specified only closes dock widgets and main windows with the specified affinities
      */
-    void clear(const QStringList &affinities = {});
+    Q_INVOKABLE void clear(const QStringList &affinities = {});
 
     /**
      * @brief clear Overload that only clears the specified dockWidgets and main windows.