QmlDesigner: Block cursor updates by ModelToTextMerger

When we update the text we have to block the cursor
selection synchronization.

Change-Id: I79c3589482f2ca884bc4980b295b18b0a8e8ef2e
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/qmldesigner/components/texteditor/texteditorwidget.h

@@ -58,6 +58,9 @@ public:
     void clearStatusBar();
 
     int currentLine() const;
+
+    void setBlockCurserSelectionSyncronisation(bool b);
+
 protected:
     bool eventFilter(QObject *object, QEvent *event) override;
 
@@ -68,6 +71,7 @@ private:
     QPointer<TextEditorView> m_textEditorView;
     QTimer m_updateSelectionTimer;
     TextEditorStatusBar *m_statusBar;
+    bool m_blockCurserSelectionSyncronisation = false;
 };
 
 } // namespace QmlDesigner