Waveform

Below the canvas, a render of the current sound playing the current notes, the demo line or the pattern. It shows what the phrase does to the audio over several passes, which live listening only lets you hear once.

The waveform of eight bars of an acid line, bar numbers along the bottom
and the playhead in bar four.

Render

Render makes the waveform. Once there is one, the button reads Re-render, and it turns to its warning colour, with the note "edited since this was rendered", as soon as the sound or the notes change. It does not render on every edit, because a render takes long enough to interrupt a drag.

Until the first render the waveform says so.

The waveform

Bar lines across the render.
Heavier lines where each phrase of the arc starts over. Either side of one is the same drawing carrying a different part of the wander.
The shaded end: the release ringing on after the notes stop. The playhead never enters it, because when looping live the tail rings across the restart instead.
The playhead, which follows the loop of the notes.

Drag along the waveform to move the playhead.