qtquick: add a way to disable the default mouse redirectors

So user can use his own

src/private/quick/qml/Frame.qml

@@ -21,6 +21,7 @@ Rectangle {
     readonly property int nonContentsHeight: titleBar.heightWhenVisible + tabbar.height
     property int contentsMargin: 2
     property int titleBarContentsMargin: 1
+    properby bool hasCustomMouseEventRedirector: false
 
     anchors.fill: parent
 
@@ -108,7 +109,8 @@ Rectangle {
 
             onTabBarCppChanged: {
                 if (tabBarCpp) {
-                    tabBarCpp.redirectMouseEvents(dragMouseArea)
+                    if (!root.hasCustomMouseEventRedirector)
+                        tabBarCpp.redirectMouseEvents(dragMouseArea)
 
                     // Setting just so the unit-tests can access the buttons
                     tabBarCpp.tabBarQmlItem = this;

src/private/quick/qml/TitleBarBase.qml

@@ -36,6 +36,9 @@ Rectangle {
     /// Don't set 'hight' directly in the overridden component
     property int heightWhenVisible: 30
 
+    /// Set to true if you're using a custom MouseEventRedirector in your code
+    property bool hasCustomMouseEventRedirector: false
+
     /// @brief Signal emitted by a TitleBar.qml component when the close button is clicked
     signal closeButtonClicked();
 
@@ -58,7 +61,8 @@ Rectangle {
 
     onTitleBarCppChanged: {
         if (titleBarCpp) {
-            titleBarCpp.redirectMouseEvents(dragMouseArea)
+            if (!root.hasCustomMouseEventRedirector)
+                titleBarCpp.redirectMouseEvents(dragMouseArea)
 
             // Setting just so the unit-tests can access the buttons
             titleBarCpp.titleBarQmlItem = this;