I have been playing with this using both Chrome and Firefox and it seems that at least Firefox sends alerts to NVDA that are then refused by
NVDAObject.Accessible.behaviour NVDA sees a pprogressbar accessible update but then seems to be looking for integer values for min, max, and value.
My reading of the ARIA specs indicate that the browsers should accet:
The behavior routine is sending a warning that the value in aria-valuetext is not a number.
I expect that the progressbar routine is what gives the tones whenNVDA is installing. So if I want to make NVDA speak not only the percentage but the aria-valuetext would I have to override the function I found and if so how would I know what thclass to inherit to get this to behave the way I would expect.