fixes position marker height on startup (#3587)

Fixes position marker height on startup

include/SongEditor.h

@@ -81,6 +81,7 @@ public slots:
 	void setEditModeSelect();
 
 	void updatePosition( const MidiTime & t );
+	void updatePositionLine();
 
 protected:
 	virtual void closeEvent( QCloseEvent * ce );
@@ -152,6 +153,9 @@ public:
 
 	SongEditor* m_editor;
 
+protected:
+	virtual void resizeEvent( QResizeEvent * event );
+
 protected slots:
 	void play();
 	void record();
@@ -162,6 +166,7 @@ protected slots:
 
 signals:
 	void playTriggered();
+	void resized();
 
 private:
 	QAction* m_addBBTrackAction;