public override void OnInspectorGUI()
    {
        m_Song.Time = EditorGUILayout.FloatField("Song lenth", m_Song.Time);                      // you can input value in the inspector.

        m_Song.RowsPerMinute = EditorGUILayout.IntField("Rows Per Minute", m_Song.RowsPerMinute); // you can input value in the inspector.

        m_NumOfRow = (int)(m_Song.Time * (float)m_Song.RowsPerMinute) + 10;                       // ask carlo about this piece of code

//		if(m_NumOfRow < m_Song.ListOfRows.Count)
//		{
//			m_Song.ListOfRows.RemoveRange (m_NumOfRow,m_Song.ListOfRows.Count - m_NumOfRow);
//		}

        for (int i = 0; i < m_NumOfRow; i++)
        {
            if (i >= m_Song.ListOfRows.Count)
            {
                Row row = new Row();
                row.AddToRows(m_Song.NumOfCol);
                m_Song.ListOfRows.Add(row);
            }

            EditorGUILayout.BeginHorizontal();

            EditorGUILayout.LabelField("Row " + i);

            for (int j = 0; j < m_Song.NumOfCol; j++)
            {
                m_Song.ListOfRows[i].RowOfNote[j] = EditorGUILayout.Toggle(m_Song.ListOfRows[i].RowOfNote[j]);
            }
            EditorGUILayout.EndHorizontal();
        }
    }