ui: Intermediate fix to avoid early QWidget deletion due to smart pointers

TODO: get rid of smart pointers for Qt classes in QtGraphView

src/lib_gui/qt/view/QtGraphView.cpp

@@ -356,6 +356,9 @@ void QtGraphView::clear()
 		m_oldActiveNode.reset();
 		m_activeNodes.clear();
 
+		m_oldOldNodes = m_oldNodes;
+		m_oldOldEdges = m_oldEdges;
+
 		m_nodes.clear();
 		m_edges.clear();
 
@@ -777,6 +780,9 @@ void QtGraphView::switchToNewGraphData()
 		edge->setParentItem(nullptr);
 	}
 
+	m_oldOldNodes = m_oldNodes;
+	m_oldOldEdges = m_oldEdges;
+
 	m_oldNodes = m_nodes;
 	m_oldEdges = m_edges;
 

src/lib_gui/qt/view/QtGraphView.h

@@ -123,9 +123,11 @@ private:
 
 	std::list<std::shared_ptr<QtGraphEdge>> m_edges;
 	std::list<std::shared_ptr<QtGraphEdge>> m_oldEdges;
+	std::list<std::shared_ptr<QtGraphEdge>> m_oldOldEdges;
 
 	std::list<std::shared_ptr<QtGraphNode>> m_nodes;
 	std::list<std::shared_ptr<QtGraphNode>> m_oldNodes;
+	std::list<std::shared_ptr<QtGraphNode>> m_oldOldNodes;
 
 	std::vector<std::shared_ptr<QtGraphNode>> m_activeNodes;
 	std::shared_ptr<QtGraphNode> m_oldActiveNode;