If this already exists then don't hesitate to embarrass me for missing this, but I think it would be really neat if one could select an option to automatically display all tags in the files loaded in the application display window, regardless if I've manually created a column to display each and every tag in the files.
Context: I subscribe to a bunch of different podcasts, and I frequently need to review tags to clean up sloppy or inconsistent tagging by the podcasters. All sorts of random tag names pop up even from long-established podcasters, so currently I need to manually enter a new tag column to look at each and every new tag to see if it's garbage or if it's another tag that was mistakenly renamed by the podcaster. It struck me that I could save a bunch of time if I could select between displaying the tags that I have already entered and chosen to display (what Mp3tag does today and makes sense as the default), or select to display all of the tags embedded in the files I'm working with even if the files contain tags that are not currently manually entered in my column display selections. This second option would eliminate the need to manually create columns for each new random tag and then delete each column after cleaning up the files.
If this does not make any sense, I'd be glad to clarify. If this seems useless, don't hold back. But if this seems helpful, that would be good to comment on as well.
Is the 'Extended Tags' dialog not sufficient? If you highlight all files and open it, you'll see all of the fields present, even if some files don't contain all of them. And it's easier to remove fields through the Extended Tags dialog than it is using the columns.
View > Extended Tags, or Alt-T, or the use 'pencil & paper' icon.
The extended tags option just tells me if a tag exsits - it reveals absolutely nothing about what it contains unless all tags have the exact same value (rarely in this case). I need to manually create a new display column to see the contents of new tags when the new tags contain differnt values, and then manually delete the column when I'm done cleaning it up or deleting it.
Foobar2000 has a version of "extended tags" that could be useful here - when you select "properties" on selected files in Foobar2000, in addition to displaying all the tags and the values of the tags for which all tags have the same value, Foobar2000 will also display in that same window the various entries in a tag even if there are different values in that tag of the same name. That saves a tremendous amount of time compared to manually creating a column in Mp3tag to learn anything about a new tag that has different data, and then manually deleting that tag display column. And no, foobar2000 cannot do many things I do in Mp3tag, so dumping Mp3tag for just Foobar2000 is not viable.