To reproduce:

1. Go to the dashboard.
2. Click on a cell on the calendar to create a new event.
3. Expand the form to display the Tiny editor
4. Press Alt-0 (or Option-0 on Mac) to show the Help modal.
5. Tab through the Help modal.
6. Expected: The focus will be locked within the modal, meaning tabbing through will move the focus only within the modal until the user presses escape or the close button to close the modal.
7. Actual: The focus moves out of the modal and can end up focusing on content behind the modal. This breaks the WCAG 2.2 Level AA Success Criterion 2.4.11 Focus not obscured.