make connections unique

GUI/View/Scene/MaskGraphicsScene.cpp

@@ -99,8 +99,8 @@ void MaskGraphicsScene::associateItems(Data2DItem* data_item)
     ASSERT(m_masks);
     ASSERT(m_prjns);
 
-    connect(m_masks, &MasksSet::setChanged, this, &MaskGraphicsScene::updateMost);
-    connect(m_prjns, &MasksSet::setChanged, this, &MaskGraphicsScene::updateMost);
+    connect(m_masks, &MasksSet::setChanged, this, &MaskGraphicsScene::updateMost, Qt::UniqueConnection);
+    connect(m_prjns, &MasksSet::setChanged, this, &MaskGraphicsScene::updateMost, Qt::UniqueConnection);
 
     updateMost();
 }