When redrawing a Climacs screen, either by hitting C-l or just moving the screen around, I consistently got an error about OUTPUT-RECORD-HASH having no applicable methods for STANDARD-BOUNDING-RECTANGLE. After a little analysis of incremental-redisplay.lisp, it looks like the first method of OUTPUT-RECORD-HASH defined in incremental-redisplay.lisp should be specialized on STANDARD-RECTANGLE, or at the very least STANDARD-BOUNDING-RECTANGLE, instead of BASIC-OUTPUT-RECORD, because it will at some point get a STANDARD-BOUNDING-RECORD that is not also a BASIC-OUTPUT-RECORD: The OLD-BOUNDS slot of UPDATING-OUTPUT-RECORD-MIXIN has an initform of a call to MAKE-BOUNDING-RECTANGLE, which returns an instance of STANDARD-BOUNDING-RECTANGLE. COMPUTE-DIFFERENCE-SET (which is where the error was signalled when Climacs borked) collects the values of OLD-BOUNDS slots into a list and then puts elements of that list as keys into a table, using OUTPUT-RECORD-HASH to convert them into keys. Unless the OLD-BOUNDS slot is meant to be a BASIC-OUTPUT-RECORD instance more specifically than a STANDARD-BOUNDING-RECORD, the method isn't specific enough to handle this. (The COORDINATES slot is defined in the STANDARD-RECTANGLE class, which is why I suggested it as the least specific possible class to specialize the OUTPUT-RECORD-HASH method on, which just returns the value of that slot.) I'm no McCLIM expert, so the solution of specializing the method differently may be the wrong thing, and the right thing may be to fix the value of the OLD-BOUNDS slot, but changing the specializer seems to work here, and I don't have any specific suggestions on fixing it the other way (changing the value of the OLD-BOUNDS slot). Can anyone else comment on this fix or, if it is the right thing, commit it? (I'm told that it's Tim Moore's code.)