diff --git a/MainWindow.h b/MainWindow.h
new file mode 100644
index 0000000..592cf78
--- /dev/null
+++ b/MainWindow.h
@@ -0,0 +1,70 @@
+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QMainWindow>
+#include <QGraphicsView>
+/* MAINWINDOW_H
+ * CLASS DECLARATION
+ *
+ * CHANGLOG:
+ * NAME:            |   CHANGES:                                                |   DATE:           |
+ * Mewes, Lars      | Neuerstellung                                             | 24.09.2021        |
+ * Mewes, Lars      | Änderung auf QTabWidget (statt QSplitter) + Midi-Versuche | 28.09.2021        |
+ *                  |                                                           |                   |
+ *                  |                                                           |                   |
+ *
+ * DESCRIPTION:
+ * Diese Klasse ist die "Hauptklasse" und besitzt die Farbtonskala "ColorScale", die QGraphicsViews sowie die Klaviatur und den Quintenzirkel
+ *
+ * TO-DOs:
+ *
+ *
+ */
+
+#include <QGraphicsScene>
+#include <QTabWidget>
+#include <QPlainTextEdit>
+#include <QThread>
+
+#include "RtMidi.h"
+
+#include "MidiListener.h"
+#include "PianoKeyBoard.h"
+#include "Tone.h"
+#include "ColorScale.h"
+#include "CircleOfFifths.h"
+
+
+class MainWindow : public QMainWindow
+{
+    Q_OBJECT
+    QTabWidget * tabWidget;
+
+    QGraphicsView * gV_Keyboard;
+    QGraphicsView * gV_CircleOfFifths;
+    QGraphicsView * gV_Demo;
+    QPlainTextEdit * midiLog;
+
+    PianoKeyBoard * pianoKeyBoard;
+    CircleOfFifths * circleOfFifths;
+    QGraphicsScene * scene_Demo;
+
+    QThread midiThread;
+    MidiListener * midiPiano;
+    void lightShowDemonstration(int b1, int b2, int b3);
+public slots:
+
+    void handleMidiMessage(int b1, int b2, int b3);
+signals:
+    void startMidiListener(int Port = 1);
+    void nextMidiMessage();
+    void stopMidi();
+public:
+
+    RtMidiIn * midiin = nullptr;
+    MainWindow(QWidget *parent = nullptr);
+    virtual ~MainWindow();
+
+    ColorScale colorScale;
+};
+#endif // MAINWINDOW_H
diff --git a/MidiListener.cpp b/MidiListener.cpp
new file mode 100644
index 0000000..1d32ba9
--- /dev/null
+++ b/MidiListener.cpp
@@ -0,0 +1,35 @@
+#include "MidiListener.h"
+#include <vector>
+#include <QString>
+void MidiListener::start(int Port){
+    midiin = new RtMidiIn(RtMidi::Api::LINUX_ALSA, "Scrjabin");
+
+     try {
+       midiin->openPort(Port);
+     }
+     catch ( RtMidiError &error ) {
+       error.printMessage();
+     }
+     emit newMidiMessage(0,0,0);
+
+};
+void MidiListener::listen(){
+    std::vector<unsigned char> message;
+
+    // Don't ignore sysex, timing, or active sensing messages.
+    midiin->ignoreTypes( false, false, false );
+
+    midiin->getMessage( &message );
+    if ( message.size() == 3 )
+        emit newMidiMessage(message[0], message[1], message[2]);
+    else
+        emit newMidiMessage(0,0,0);
+};
+void MidiListener::stop(){
+    delete midiin;
+    this->disconnect();
+    this->~MidiListener();
+}
+MidiListener::~MidiListener(){
+
+}
diff --git a/MidiListener.h b/MidiListener.h
new file mode 100644
index 0000000..7660b94
--- /dev/null
+++ b/MidiListener.h
@@ -0,0 +1,17 @@
+#pragma once
+#include "RtMidi.h"
+#include <iostream>
+#include <QObject>
+
+class MidiListener: public QObject{
+    Q_OBJECT
+    RtMidiIn * midiin;
+public:
+    ~MidiListener();
+public slots:
+    void start(int Port = 0);
+    void listen();
+    void stop();
+signals:
+    void newMidiMessage(int b1, int b2, int b3);
+};
diff --git a/PianoKey.cpp b/PianoKey.cpp
new file mode 100644
index 0000000..05ea738
--- /dev/null
+++ b/PianoKey.cpp
@@ -0,0 +1,27 @@
+#include "PianoKey.h"
+#include <QBrush>
+
+PianoKey::PianoKey(Tone *tone): tone(tone){
+    if(tone->getFlatTone()){
+        setRect(-350+tone->getKeyboardPosition()*100,0, 100, 700);
+
+    }
+    else{
+        setRect(-350+75+tone->getKeyboardPosition()*100,0, 50, 500);
+        setZValue(1);
+    }
+    setBrush(QBrush(tone->getColor()));
+};
+PianoKey::~PianoKey(){};
+
+Tone * PianoKey::getTone()const{
+    return tone;
+};
+
+//SLOTS:
+void PianoKey::redraw(){
+    setBrush(QBrush(tone->getColor()));
+};
+
+
+
diff --git a/PianoKey.h b/PianoKey.h
new file mode 100644
index 0000000..f7f4895
--- /dev/null
+++ b/PianoKey.h
@@ -0,0 +1,39 @@
+/* PIANOKEY_H
+ * CLASS DECLARATION
+ *
+ * CHANGLOG:
+ * NAME:            |   CHANGES:                                                |   DATE:           |
+ * Mewes, Lars      | Neuerstellung                                             | 24.09.2021        |
+ *                  |                                                           |                   |
+ *                  |                                                           |                   |
+ *                  |                                                           |                   |
+ *
+ * DESCRIPTION:
+ * Diese Klasse enthält analog zu "CircleElement" alle Bestandteile einer Klaviertaste.
+ *
+ * TO-DOs:
+ * Beschriftung auf den Tasten ergänzen
+ *
+ */
+#pragma once
+
+#include <QGraphicsRectItem>
+#include <QString>
+
+#include "Tone.h"
+
+class PianoKey: public QObject, public QGraphicsRectItem{
+    Q_OBJECT
+
+    Tone * tone;
+public:
+
+    PianoKey(QString _tone, int pos, QColor _col, bool flatTone = true);
+    PianoKey(Tone * tone);
+    virtual ~PianoKey();
+
+    Tone * getTone()const;
+
+public slots:
+    void redraw();
+};