In slime.el, two customization groups are defined:

| (defgroup slime nil | "Interfaction with the Superior Lisp Environment." | :prefix "slime-" | :group 'applications)

| (defgroup slime-debugger nil | "Backtrace options and fontification." | :prefix "sldb-" | :group 'slime)

However, all debugger-related options belong to group sldb, not slime-debugger, e.g.:

| (defcustom sldb-enable-styled-backtrace t "Enable faces in slime backtrace" | :type '(choice | (const :tag "Enable" t) | (const :tag "Disable" nil)) | :group 'sldb)

The result is that the slime group has a link to the slime-debugger group, which is empty, and to customize the debugger options one has to invoke (customize-group 'sldb) directly.

It seems to me that either the group on all these options should be changed to slime-debugger, or the group slime-debugger should be renamed to sldb.