Hello.
First I wont to thank the OpenMPT developers for this great piece of software.
Indeed, OpenMPT is the only tracker which is already somewhat accessible for blind users thanks to extensive use of native windows controls, but some of its parts are quite inconvenient to interact with for a screen reader user. This is especially true for the editor views.
I have just made an add-on for the open source NVDA screen reader which makes OpenMPT more accessible for the blind and visually impaired.
Currently this add-on is quite primitive, but it's already usable.
With this add-on NVDA is able to automatically announce current row / channel info when inputting / navigating in the pattern editor, report instrument envelope points, read the order list and possibly some other things.
Also, this add-on works around some keyboard focus problems, e.g. when going to the comments tab or the OPL instrument editor.
This is my first NVDA add-on, and I'm not a programmer at all, that's why the code is terrible. But it is surprisingly working.
It would be great if OpenMPT developers implement proper accessibility interfaces for all the custom controls they use, but for now we need to constantly use focus reporting commands or better write our own screen reader add-ons.
I've seen some accessibility related topics here, so here's a link for whose who are interested.
https://drive.google.com/open?id=1TKW2mJcQ0LG97XNj_yo2ON-xmyoQJLZZ