DatabaseWindow has no knowledge more of the existence of QueryTab but user can still create and use them within that window.

pglab/plugin_support/IPluginContentWidgetContext.h

@@ -47,6 +47,10 @@ public:
 
 	virtual void addContentWidget(PluginContentWidget *widget) = 0;
 
+	/** Return a widget you can use as a parent
+	 */
+	virtual QWidget* container() = 0;
+
 	template<typename T, class...Args>
 	bool addObjects(Args&&...args);
 	template<typename T>