QmlDesigner.PropertyEditor: Adding signal selectionToBeChanged

Controls can connect to this signal and commit data to the backend
before the slection changes.
This is required since editingFinished signals are usually triggered to
"late".

Change-Id: I99fa27064473ceee2d1a21b25f64a13370fb4cef
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>

src/plugins/qmldesigner/components/propertyeditor/propertyeditorqmlbackend.cpp

@@ -437,6 +437,11 @@ bool PropertyEditorQmlBackend::checkIfUrlExists(const QUrl &url)
     return (QFileInfo(fileFromUrl(url)).exists());
 }
 
+void PropertyEditorQmlBackend::emitSelectionToBeChanged()
+{
+    m_backendModelNode.emitSelectionToBeChanged();
+}
+
 QUrl PropertyEditorQmlBackend::getQmlUrlForModelNode(const ModelNode &modelNode, TypeName &className)
 {
     if (modelNode.isValid()) {

src/plugins/qmldesigner/components/propertyeditor/propertyeditorqmlbackend.h

@@ -74,6 +74,8 @@ public:
 
     static bool checkIfUrlExists(const QUrl &url);
 
+    void emitSelectionToBeChanged();
+
 private:
     void createPropertyEditorValue(const QmlObjectNode &qmlObjectNode,
                                    const PropertyName &name, const QVariant &value,

src/plugins/qmldesigner/components/propertyeditor/propertyeditorview.cpp

@@ -577,6 +577,9 @@ void PropertyEditorView::scriptFunctionsChanged(const ModelNode &/*node*/, const
 
 void PropertyEditorView::select(const ModelNode &node)
 {
+    if (m_qmlBackEndForCurrentType)
+        m_qmlBackEndForCurrentType->emitSelectionToBeChanged();
+
     if (QmlObjectNode(node).isValid())
         m_selectedNode = node;
     else

src/plugins/qmldesigner/components/propertyeditor/qmlmodelnodeproxy.cpp

@@ -50,4 +50,9 @@ void QmlModelNodeProxy::registerDeclarativeType()
     qmlRegisterType<QmlModelNodeProxy>("HelperWidgets",2,0,"ModelNodeProxy");
 }
 
+void QmlModelNodeProxy::emitSelectionToBeChanged()
+{
+    emit selectionToBeChanged();
+}
+
 }

src/plugins/qmldesigner/components/propertyeditor/qmlmodelnodeproxy.h

@@ -47,8 +47,11 @@ public:
 
     static void registerDeclarativeType();
 
+    void emitSelectionToBeChanged();
+
 signals:
     void selectionChanged();
+    void selectionToBeChanged();
 
 public slots: