Hallo,
SBCL has recently deprecated the EXIT function, reserving it for internal use. This causes package-lock errors in LTK when LTK is loaded from Quicklisp.
I have prepared a patch for this; however, I am sufficiently unfamiliar with the internals (and have not used COMPUTE-BUTTONS) to only claim that it compiles.
I ran a few examples from the docs and they worked successfully.
I also suspect (but am not sure) that line ltk.lisp:4189 in SVN version 261 will also have to be changed.
Regards, Paul Nathan