Remove instrument track window caching to fix related bugs (#5808)

include/InstrumentTrack.h

@@ -42,7 +42,6 @@
 
 
 class QLineEdit;
-template<class T> class QQueue;
 class InstrumentFunctionArpeggioView;
 class InstrumentFunctionNoteStackingView;
 class EffectRackView;
@@ -324,10 +323,6 @@ public:
 		return m_midiMenu;
 	}
 
-	void freeInstrumentTrackWindow();
-
-	static void cleanupWindowCache();
-
 	// Create a menu for assigning/creating channels for this track
 	QMenu * createFxMenu( QString title, QString newFxLabel ) override;
 
@@ -349,12 +344,12 @@ private slots:
 	void assignFxLine( int channelIndex );
 	void createFxLine();
 
+	void handleConfigChange(QString cls, QString attr, QString value);
+
 
 private:
 	InstrumentTrackWindow * m_window;
 
-	static QQueue<InstrumentTrackWindow *> s_windowCache;
-
 	// widgets in track-settings-widget
 	TrackLabelButton * m_tlb;
 	Knob * m_volumeKnob;
@@ -482,6 +477,7 @@ private:
 	PianoView * m_pianoView;
 
 	friend class InstrumentView;
+	friend class InstrumentTrackView;
 
 } ;