make main_layout protected

include/richtexteditordialog.h

@@ -11,6 +11,7 @@
 class RichTextEditorDialog : public QDialog
 {
     Q_OBJECT
+
 public:
     explicit RichTextEditorDialog(QWidget *parent = nullptr);
     ~RichTextEditorDialog();
@@ -31,9 +32,11 @@ private:
     RichTextEditor *m_editor;
     QTextEdit      *m_text_edit;
     QTabWidget     *m_tab_widget;
-    QVBoxLayout    *m_main_layout;
     State m_state;
     int m_initialTab;
+
+protected:
+    QVBoxLayout    *m_main_layout;
 };
 
 #endif // RICHTEXTEDITORDIALOG_H