1574079 - Make the performance modal keyboard-modal, too, and label its Close button for accessibility

Status: NEW

(DevTools :: about:debugging, enhancement, P2)

Description

[Marco Zehe (:MarcoZ)]

While Ola and I were testing about:debugging with the NVDA screen reader, and testing the performance of a connected device, we found that the modal that pops up and from where you can get to the profiler, has a problem with keyboard focus. It allows keyboard focus to move outside the modal and activate other things that are behind the modal.

Instead, it should trap focus. From the Close button, the next Shift+Tab should wrap around to the bottom to the last focusable item, and likewise, when on the last focusable item, the next press of the tab key should wrap around to the top of the dialog onto the first focusable item. Keyboard focus should not be allowed to move outside the modal. The Close button should be the only means to get focus out.

After the Close button has been pressed and the dialog dismissed, focus should then move back to the button that opened it. Right now, it stays in limbo after the dialog closes. But a keyboard user should go back to where they opened the dialog from, the Performance button in the main UI for a connected device.

Also, while you're here, give the graphical Close button a text equivalent so the Name property of the Button accessible has a value other than null. Probably a case for a localized aria-label string, or if it's an image, the alt attribute for that image.