Re: Emacs hangs enabling debug-on-error

[Richard Stallman]

    >     The problem is that redisplay triggers an error which throws to
    >     top-level while input is blocked, and we don't unblock input in that
    >     case.

    I have just installed a fix for this (in recursive-edit and top-level).

Would you please show me this change?

That may not entirely fix the bug.  It may be a bug just to run LIsp
code in the middle of updating non-Lisp data structures, such as
occurs in the toolbar code.  So even if your change is an improvement,
we probably need to fix the code in xdisp.c as well.