Focus and Combobox Interaction with Mobile VoiceOver

Hi Folks,
I have a question about how strict focus should be kept on a list of options in a combobox interaction. 

The PhET Sim Molarity is implemented with interactive description that can be accessed with four screen reader/browser combinations: NVDA & Firefox, JAWS & Chrome, VoiceOver & Safari, and Mobile VO & Safari on iOS. My question is specifically about Mobile Voice on iOS.

Link to Molarity: https://phet-dev.colorado.edu/html/molarity/1.6.0-dev.1/phet/molarity_en_phet.html?a11y <https://phet-dev.colorado.edu/html/molarity/1.6.0-dev.1/phet/molarity_en_phet.html?a11y>

The combobox interaction for choosing a new solute is based on the the accessible design pattern used here:
https://www.w3.org/TR/wai-aria-practices/examples/listbox/listbox-collapsible.html <https://www.w3.org/TR/wai-aria-practices/examples/listbox/listbox-collapsible.html>

The issue that we have found is that when using Mobile VoiceOve it is possible for the list of options to stay open and still move focus over to a slider and interact with the slider.

My question is, would it be better to treat the popped-up list of solutes like a dialog and prevent access to the rest of the sim while the list of options is open?

Currently, we are using focus, so when the list loses focus it closes, but this doesn’t seem to work with Mobile VoiceOver.

Any thoughts?

Taliesin Smith

~.~.~
Also available off list at:
[email protected]
Inclusive Design Researcher
PhET Interactive Simulations
https://phet.colorado.edu/en/accessibility
Physics Department
University of Colorado, Boulder