It's unbelievable, but even with this remove/undo function, I don't get the Remark tag viewable in Windows Explorer.
The only way to see it in Explorer is to remove de ID3v2 tag in WinAmp and then re-add it by copying from the ID3v1 tag also in Winamp. But like this I loose some extra tags from the ID3v2 format AND I need to KNOW which files are like this!
After this I noticed in mp3trag that the IDtag size remains the same: 2061 Byte.
I also tried the id3clean.exe tool with -compact option but that doesn't help either.
(see post how to reduce filesize after deleting unwanted tags?
This tool can remove the unused padding in the tags, fine to reduce the filesize a little more. A shame it doesn't has a windows shell, maybe this also would be a nice feature for mp3tag to include.