@vsverchinsky . There's a problem with the tab order.

If the "add new location" for the VST plugins is the focus, then if a user presses Tab, then the "add new location" button for the VST3 plugins becomes the focus, rather than the text box. This is a confusing reading order for users of screen readers - and it looks pretty odd as well.

@vsverchinsky

When submitting the new plugin locations, then removing one of them and clicking OK button, Audacity crashes:

After adding a plugin location for LADSPA, then for LV2 and then clicking the Remove button for LV2, the previously added LADSPA location is deleted instead:

When adding new plugin locations, the bottom of the screen gets squashed:

@vsverchinsky If more than one directory is added for the same plugin family, the new text boxes are put on top of the rest, taking away all available space with each newly added line:

@vsverchinsky

Windows:

• I provided 4 custom locations, one per family (LADSPA, LV2, VST, VST3); Only 2 of those directories - VST and VST3 - had files in them, the rest were empty. Then I closed the Preferences windows by clicking OK and then tried to run Rescan in the Plugin Manager. Result: a crash

macOS:

• I entered and saved new custom locations for LV2, LADSPA, VST, and VST3, with plugin files in each of them. Then I ran Rescan, and as a result, only in the LADSPA, LV2 and VST3 directories, the plugins were found. The plugins in the custom VST directory were not discovered during the rescan.

@vsverchinsky one of the previously reported issues remains unfixed: on macOS, a custom VST path is still being ignored and the plugins in it aren't found.

Tested. All previously reported problems have been fixed.