Adds initial intermediate qt6 porting state

qt6-after/qt6-migrated-legatus/Lts/Common/TopicEditorBase/topic_previewer.h

@@ -0,0 +1,38 @@
+#pragma once
+
+#include "topic_editor_utils.h"
+
+#include <TopicEditorBase/topiceditorbase_export.h>
+
+#include <QWidget>
+
+
+namespace TopicEditorBase
+{
+
+class TOPICEDITORBASE_EXPORT TopicPreviewer : public QWidget
+{
+  Q_OBJECT
+
+public:
+  explicit TopicPreviewer(QWidget *parent = nullptr);
+  ~TopicPreviewer();
+
+  void setTopicData(const TopicData &data);
+  TopicData topicData() const { return m_topicData; }
+
+protected:
+  void mousePressEvent(QMouseEvent *event) override;
+  void paintEvent(QPaintEvent *event) override;
+
+signals:
+  void startDragMe();
+  void stopDragMe();
+  void deleteMe();
+
+private:
+  TopicData m_topicData;
+
+};
+
+}