• Access key + w focuses the widget

Closed popup:

• left arrow highlights previous selected item
• right arrow highlights next selected item
• home highlights first selected item
• end highlights last selected item
• delete deletes highlighted item
• backspace deletes previous selected item
• down arrow opens the popup
• esc clears highlighted item

Opened popup:

• up arrow highlights previous item
• down arrow highlights next item
• home highlights first item in the popup
• end highlights last item in the popup
• enter selects highlighted item
• esc closes the popup
• up arrow closes the popup if the first item is highlighted