In Staventabs Pro, you do not choose the symbol for a rest, instead you mark the position as containing a rest. The rest symbol is determined automatically according to the note value of its position, which can be changed in the Note values pane.
- Allocate a space for a rest by pressing the Right Arrow key.
- Click the Rest button in the right sidebar to add a quarter rest.
- To change the duration of the rest to half (1/2), click the Half button in the Note values pane.
- You can remove a rest from the staff by clicking the highlighted Rest button.
- To undo the last action and bring the rest symbol back, press Command‑Z  .