Hi Alistair
Thanks for your response.
I've just had another look. We were jumping between screen readers and browsers at the time and I've clearly got confused at some point, I do apologise. You are quite correct, keyboard navigation does include closing pop-up windows in both IE and Chrome, although there is no coloured highlight box in IE making it a little tricky to know where you are sometimes.
Our issues clearly occurred when using Read&Write screen reader. This can be a bit fussy in Chrome and we had very little success with the Xerte / Chrome / Read&Write combination.
It was in IE that Xerte and Read&Write did work but we lost some of the focus points, including closing the text pop-ups and audio controls.
Clearly, there's nothing we can do about this but at least we know what it was now.
I do wonder about tab sequence though, for next/back navigation. On a plain text page, there is a minimum of 6 TAB key presses to reach the NEXT button. Would it be totally illogical to go to back/next before the help/screen size/accessibility/contents buttons? Just raising the thought, really.
Realistically, it looks unlikely that we will pursue this at the moment as there just isn't a great enough need to justify the time required. The Grid ticks enough of the boxes for our students, for now. This was an interesting exercise, however, and I hope it might be of use to you at some stage.
Many thanks
Vicky