[MIT-Scheme-devel] ancient bug

[Taylor R Campbell]

In microcode/x11base.c, xd_process_events has been broken for twenty
years: the logic to handle XD_CACHED_EVENT never actually uses the
event structure cached in XD_CACHED_EVENT, and instead uses whatever
it finds in the uninitialized variable `event'.

I'm about to change xd_process_events anyway, to kill UX_select_input,
so I'll just fix this in the process, but...yikes.  Fortunately this
is a relatively uncommon code path, and it doesn't lead to following
bogus pointers, so it probably just caused very infrequent flakiness
in Edwin.