Activate the button labeled "Trigger Progressbar". A progressbar will appear and automatically increase it's value up to a 100%. This takes about 12 seconds. While the progressbar is being shown, keyboard interaction is prohibited.
The Progressbar widget does not require any keyboard shortcuts.
To be announced properly, the an ARIA compliant screen reader must be used that will correctly announce progressbar updates.
The menubar takes up one stop in the tab order, can can be navigated with the following keyboard shortcuts: