QmlDesigner: crash fix

See BAUHAUS-435
Inside a modification group/transaction we disable undo/redo

src/plugins/qmldesigner/components/integration/designdocumentcontroller.cpp

@@ -748,11 +748,13 @@ RewriterView *DesignDocumentController::rewriterView() const
 
 void DesignDocumentController::undo()
 {
+    if (m_d->rewriterView && !m_d->rewriterView->modificationGroupActive())
         m_d->textEdit->undo();
 }
 
 void DesignDocumentController::redo()
 {
+    if (m_d->rewriterView && !m_d->rewriterView->modificationGroupActive())
         m_d->textEdit->redo();
 }
 

src/plugins/qmldesigner/core/include/rewriterview.h

@@ -153,6 +153,7 @@ public:
     int nodeLength(const ModelNode &node) const;
     int firstDefinitionInsideOffset(const ModelNode &node) const;
     int firstDefinitionInsideLength(const ModelNode &node) const;
+    bool modificationGroupActive();
 
 signals:
     void errorsChanged(const QList<RewriterView::Error> &errors);

src/plugins/qmldesigner/core/model/rewriterview.cpp

@@ -484,6 +484,11 @@ int RewriterView::firstDefinitionInsideLength(const ModelNode &node) const
     return objectLengthCalculator(offset);
 }
 
+bool RewriterView::modificationGroupActive()
+{
+    return m_modificationGroupActive;
+}
+
 void RewriterView::qmlTextChanged()
 {
     if (inErrorState())