GH-1652 save all instance settings on launch if instance window is already open

application/widgets/PageContainer.h

@@ -41,7 +41,11 @@ public:
 
 	void addButtons(QWidget * buttons);
 	void addButtons(QLayout * buttons);
-	bool requestClose(QCloseEvent *event);
+	/*
+	 * Save any unsaved state and prepare to be closed.
+	 * @return true if everything can be saved, false if there is something that requires attention
+	 */
+	bool prepareToClose();
 
 	virtual bool selectPage(QString pageId) override;