r</strong> is a useful tool for editing the percussion tracks. It can alse edit the ordinary tracks, but it is much less useful. It is accessed by the <strong>View → Show Matrix</strong> menu.</p>
    <p>Basically, it divides the current measure into segments and displays the possible percussion sounds. Not only you can view the measure and the sounds in the matrix, but by clicking on one block of the matrix you add/remove the sound from the tab.</p>
    <img src="images/matrix_editor.png" />
    <p>It is