(1) attributes "System append only" and "System Immutable" can only be removed/unset when booted into single-user mode, so I believe it would be better to change them to read-only in Nimble Commander, i.e. make the tick boxes greyed-out and non-interactive, because you won't be able to change anything in NC anyway, not even in Admin Mode
(2) According to stat.h – https://opensource.apple.com/source/xnu ... .auto.html – the attribute "User Tracked" (UF_TRACKED) has become irrelevant, because macOS "no longer issue[s] notifications for deletes or renames for files which have UF_TRACKED set." Furthermore, the attribute has never shown up in ls -laO, so I'm not sure what should be done with it. Read-only maybe? I guess the user can set the "tracked" attribute, but what's the use outside of Nimble Commander?
(3) "System No Unlink", a valid macOS file attribute, sunlnk with chflags, is missing from Nimble Commander's Attributes panel/window. (It's a system attribute.) Make sure to not include "User No Unlink", uunlnk, because that's FreeBSD only, and it's not part of macOS. (For once, this was a good move by Apple, because setting "No Unlink" should always be done as root.
)(4) macOS also has the "restricted" attribute (files protected by SIP, I assume), and it's currently not supported by Nimble Commander. You can set and unset the attribute with root privileges (sudo) in the shell, so it should be "System Restricted" and not greyed-out in NC. (You probably need to have SIP disabled to change this attribute.)
(5) "User Compressed" should be shown as just "Compressed", because in the ls output that's how HFS+ compressed files register. Btw: with the 3rd-party afsctool it's possible to HFS-compress files on macOS in the user space, so in principle it would be possible to make the "Compressed" attribute tick box interactive, and add an HFS compression functionality to NC. However, I would wait until APFS and see if compression is still implemented. Rumor has it that "compressed" will be (finally!) dropped in favor of sparse files, which would introduce the "sparse" attribute to macOS. We'll see.
(6) GENERAL NOTES: it would be nice to have two sections in the Attributes window, one for the user attributes, then a separator line, and the next section for the system attributes; e.g. "Archived" is only for root, and "Opaque" is a user attribute, so a Nimble Commander user would know immediately if he needs to switch to Admin Mode to set or remove an attribute.
(7) MAYBE: maybe there should even be a third section for file attributes not native to macOS, but encountered on other file systems, like "snapshot" & "uunlnk", "sparse", "noarchive" etc. Btw: "snapshot" & "sparse" might make an entrance with APFS. We'll see. I was not able to test it, because I don't have access to "foreign" file systems, but it would astonish me, if macOS weren't able to read file attributes native to other file systems than HFS. (Maybe not all of them, but at least BSD.) Unless macOS has a secret way of setting/unsetting foreign attributes, this should only be read-only in Nimble Commander.
