[BUG] Accessibility feedback

[pitermach]

Hello,

First of all thanks for considering accessibility for your plugins, it's seriously appreciated and I had a blast experimenting with Tape getting some very wonderfully gritty results.

I had a look at the plugin on both Windows and Mac OS. On WIndows I used both Narrator and NVDA which is a more commonly used free screen reader than narrator. Here's a couple of observations:

The tabs - on both platforms there's no indication that a tab is selected, they all appear as a regular button to screen readers. Perhaps exposing them as radio buttons to accessibility would help, then the active tab could get the "checked" state

The toggle controls are spoken weirdly on Mac. For example, the toggle for the tape section on Windows is read out as "Toggle button pressed tape on/off" by NVDA if it's on. VoiceOver reads it out as "1, tape on/off button" instead. So on Windows they get the proper toggle roll, while on Mac for some reason they show up as a button and if they're turned on a "1" is spoken in-front of it.

Control labels on Windows - On Mac, the sliders are labeled nicely. Their label and value are read out, and if the option to read help text is on in VoiceOver then what I'm guessing is the help tooltip is also read out". On Windows, what's supposed to be the slider's label gets exposed as the controls description. NVDA and narrator read it only if you have the option to read descriptions checked which not everyone may have. Otherwise all you get is the slider's value.

Tab and arrow key navigation - Not all controls can be reached with tab. If I focus one of the tabs, then try to tab through the interface, the focus just loops between the tabs. If I focus one of the other controls and tab, then I can move between most other controls except the tabs, while instead of focusing the sliders I focus a text field for value entry instead.

What I would expect to happen is tabbing moves me through all controls on the screen and focuses the actual sliders. If a slider is focused I should be able to adjust it with up/down arrow keys, while getting the typein could be accessed IE by pressing enter on a slider. Pressing enter should also toggle the various toggle controls in the interface. Getting good tab/arrow implementation is particularly important because while on Mac people generally navigate and activate controls through VoiceOver keyboard shortcuts, Windows Screen Readers rely much more on applications themselves having good keyboard support. As a result, while you can navigate the controls with NVDA specific keys, it has no way to manipulate a slider