Hi vivo,
Thanks again for your constant work and dedication. Just did some testing on our favourite little music player (v24). I really want to help you improve the app and, as a UI designer, here are my thoughts:
The dark UI is a really nice approach with no eye strain for me and has only one major bug and few little ones:
* most important one: the playlist doesn't save the tabs for me; I've set only to have Status/Artist/Title/Length and upon closing and opening the app, all the tabs are active again; besides saving the active/inactive state and length/position values for the tabs, it would be nice to also have bitdepth and samplerate options here if easily possible
* closing and opening the folders tab maximizes the info, two clicks on the info button are needed to minimize it again; would you put an option to disable it entirely, please?
* total duration overlaps for 100+ hours
* the separating line between the folders and playlist should have a solid color, like the 1 pixel line above the tab titles, code #1e1e1e
* minor inconvenience: when having set in System Preferences/General another Highlight Color besides Blue the playlist text gets harder to read; a solution would be to have #1e1e1e font color for selection and playing status icon
* the PRE/POST text is also a bit hard to read; maybe keep only the level meters, and ditch the button and grey background; the button could become a menu entry
* suggestion for status bar: keep only the total time (right aligned), level meters (left aligned) and move the rest to the title bar; title example: "Goju - [2010-07-20] Migrations Radio Show | 1:09:01 | 16 bit | 44.1 kHz"
* suggestion for current time: a time elapsed example would be "0:13:50 | 1:09:01" and a time remaining one "-0:55:11 | 1:09:01"; total duration could be optional but the rounded rectangle stroke around the time should not be displayed as it adds clutter to this minimalistic design
* the white scroll bar kind of breaks the dark UI design, are there other color options for it ?
* the current time is the only UI element that I found using another font; you should keep just one font in the app and work only with different sizes with bold/regular
I'll stop here for now. It was supposed to be a shorter post but I got carried away

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These are just my thoughts and suggestions, everyone, please feel free to comment upon them.
Check the two attached pics, the second one is a fake with some playlist fixes.
As always, thanks a lot for your work and I hope this helps.