This would be much easier to work with files, to see the details and information of files, rather than the "pop-up" Extended Tab view.
See the below generic mockup of something how it could look and be like.
(BTW, the extended tab window would of course also be on the LEFT side, replacing the standard window when selected, I just put the two windows all in one picture for ease of viewing)
Note also I show an "alternative" version of Tabs, to use "Buttons" instead. Might be easier/less work to create than creating the tabs? And of course we aren't losing "space" in that left window section either by using buttons as we would with Tabs. There's enough space in the button bar I think, so it doesn't "have" to be tabs?
The important thing is I really would like to have the Extended Tag Info section to be in that Left Window section also so it's super fast and easy to see all the info for each selected music file.
Oh, and this could even be a "setting" I'm sure? If some people like the pop-up window better?
Though, don't know why, the window just makes it harder to click through/work with files. Though, when I think about it, this new UI could still be there, and then the "pop-up" Extended view window can "still" be used for those who like that method. People don't "have" to click the Tab or Button. So, that's likely the best way to implement this?
Hope you like this idea and will improve the program accordingly... Thanks much!