manual volume creation behavior in legacy UI
In the "Member Disks" section, if you highlight a drive, it is removed from the"ZFS Extra" list.
In the "ZFS Extra" section, if you choose a drive, it IS NOT removed from the "Members Disks" section.
This, ultimately, causes confusion and allows the user to make irreversible changes to their zpool.
If selecting a disk in the "ZFS Extra" section, it should remove that disk from the "Members Disks" section.