I haven’t mention before: on my mac, having a high-resolution Retina display and running Mac OS X 10.11.6, the Plugins… Classical Extras… UIs are poorly laid out and partially hard to read.
On the Artists tab, the UI layout is slightly wider and about 40% taller than the space in the Picard window. This means I get horizontal scroll bars, with an X-windows rather than Mac appearance. Yet there is a margin around the UI layout, which wastes space. I would prefer it if the UI adapted itself to the available space so that it did not need a horizontal scroll bar, and the vertical scroll bar matched the host OS conventions.
There is tiny, illegible text in a few places: In the “Tag mapping” tab, in the peach-coloured section at the bottom which talks about “tag mapping”; and in the entirety of the “Help” section. Interestingly, the other text is reasonably-sized and legible. Is the tiny text perhaps being specified in pixel terms? The pixels on the mac’s Retina display are about half the size of pixels in most displays.