Initial item highlight is broken until first selection is made

[oliverfoster]

Subject of the issue

If using the keyboard up/down arrows, the item highlighting does not show until an initial selection is made.

Seems to have been introduced in adaptlearning/adapt-contrib-vanilla#507

Where .dropdown__btn.is-selected + is not valid until an initial selection.

[kirsty-hames]

Yep this is due to Fix 2: Only apply selected styles when a dropdown item has been selected of the above PR. If we revert the line above however, the issue still stands that there's no distinguish between the selected option and the focused option.

This is due to aria-selected="true" being applied to the focused option rather than the selected option only.

To replicate, you can inspect the listbox .dropdown__list (expand so all .dropdown-items are visible) in you devtools. In your course, navigate to the listbox via keyboard, select enter to expand. Use up/down arrows to navigate the options. As per the video below, aria-selected="true" chases the option with focus. In the video, I selected the last option '2015' prior to hitting record. I didn't make a selection during the video so aria-selected="true" should have remained on the last option.

keypress_focus.mov

Note, if no options are selected before the listbox receives focus, the first option receives focus. There's no requirement for an option to be automatically selected (mdn listbox keyboard interactions for ref).

I'll review this against https://www.w3.org/WAI/ARIA/apg/patterns/combobox/examples/combobox-select-only/ as per #147

[oliverfoster]

Yes. It currently doesn't distinguish between highlighted/focused and selected. That is as designed.

If I remember correctly, it was an issue with the placeholder text not being an acceptable entry in the list, such that once open it should not be possible to close the dropdown without making a valid selection.

Should it be able to be closed without making a selection? The should it return to the placeholder text, etc?

[kirsty-hames]

Please ignore my comment above @oliverfoster, this is separate to this issue and will address in #147. I'll raise a PR on Vanilla to address this issue.