Debug on signal + X menubar == assertion failure

I've got a freshly compiled XEmacs from mercurial head. If I evaluate this in *scratch*, I get the expected result: (truncate-string-to-width "j.\n\n" 40 nil nil t) "j. " If I select Options->Troubleshooting->Debug on Signal, then try to evaluate that again, I get this: Debugger entered--Lisp error: (args-out-of-range "j. " 4) byte-code("..." [last-idx last-column end-column ch idx column char-width str] 3) truncate-string-to-width("j.\n\n" 40 nil nil t) eval((truncate-string-to-width "j.\n\n" 40 nil nil t)) eval-interactive((truncate-string-to-width "j.\n\n" 40 nil nil t)) eval-last-sexp(t) #<compiled-function (from eval-print-last-sexp) nil "...(13)" [standard-output terpri eval-last-sexp t] 2 1409437 nil 0x8b6>() call-interactively(eval-print-last-sexp) (dispatch-event "[internal]") This is causing the following practical problem. With an X11 build and Debug on Signal active, clicking on the menubar causes an immediate crash due to an assertion failure. A little debugger work shows the following sequence. Inside of button_item_to_widget_value (src/gui-x.c), the default-menubar from lisp/menubar-items.el is evaluated, down to one of the calls to: (truncate-string-to-width (abbrev-string-to-be-defined nil) 40 nil nil t) The abbrev-string-to-be-defined call returns "j.\n\n" (which doesn't seem right; where did that come from?). Evaluating truncate-string-to-width triggers the args_out_of_range, thereby unwinding the stack up to the call_trapping_problems call in menu_item_descriptor_to_widget_value (menubar-x.c). Since retval is unbound, this function returns NULL, and therefore compute_menubar_data also returns NULL. This triggers the assert() in set_frame_menubar (menubar-x.c) just after the call to compute_menubar_data and *boom* goes XEmacs. -- Jerry James http://www.jamezone.org/ _______________________________________________ XEmacs-Beta mailing list XEmacs-Beta(a)xemacs.org http://lists.xemacs.org/mailman/listinfo/xemacs-beta