XGContextEvent bug

[Enrico Sersale]

When GWorkspace begin a file operation, ex. move a file, it launches a
tool, "backgrounder", that perform the operation.

The app and the tool communicates throught a NSConnection.

This to inform the app of the state of the operation, wich file is moved,
is an error has occurred, etc.

The app updates the Processes Window or shows alert panels and returns
the result to the tool.

Well, while updating the processes window doesn't create problems, from
some days, a crash happens when an alert panel is shown.

The thing is perfectly reproducible:

Try to move or copy a file from a location to a folder where an
other file with the same name already exists.

You'll get an alert with something like: @"Some items have the same
name;\ndo you want to sobstitute them?"

At this point, if you press "Ok" or "Cancel" with the mouse, nothing wrong
happens and the file operation goes on.

But if you use the keyboard to confirm the app crashes:

#0  0x403d8c20 in _NSRemoveHandler (handler=0xbfffe840) at
NSException.m:272
#1  0x40412a1f in -[NSRunLoop acceptInputForMode:beforeDate:]
(self=0x81bbaf8,
    _cmd=0x404c0880, mode=0x819e128, limit_date=0x861d9b0) at
NSRunLoop.m:1424
#2  0x40412cbb in -[NSRunLoop runMode:beforeDate:] (self=0x81bbaf8,
    _cmd=0x4029edc8, mode=0x819e128, date=0x81bcee0) at NSRunLoop.m:1487
#3  0x40125f49 in -[NSGraphicsContext(Ops)
DPSGetEventMatchingMask:beforeDate:inMode:dequeue:] (self=0x824fb68,
_cmd=0x407afe20, mask=4294967295,
    limit=0x81bcee0, mode=0x819e128, flag=1 '\001') at
NSGraphicsContext.m:2358
#4  0x40773410 in -[XGContext(X11Ops)
DPSGetEventMatchingMask:beforeDate:inMode:dequeue:] (self=0x824fb68,
_cmd=0x4027e520, mask=4294967295, limit=0x81bcee0,
    mode=0x819e128, flag=1 '\001') at SharedX/XGContextEvent.m:1722
#5  0x400c0ff6 in DPSGetEvent (ctxt=0x824fb68, mask=4294967295,
    limit=0x81bcee0, mode=0x819e128) at
../Headers/AppKit/DPSOperators.h:2563
#6  0x400bc2b0 in -[NSApplication
nextEventMatchingMask:untilDate:inMode:dequeue:] (self=0x8257f30,
_cmd=0x4027ec00, mask=4294967295, expiration=0x81bcee0,
    mode=0x819e128, flag=1 '\001') at NSApplication.m:1349
#7  0x400babec in -[NSApplication run] (self=0x8257f30, _cmd=0x80f21f8)
    at NSApplication.m:893
#8  0x804c525 in main (argc=1, argv=0xbfffed34, env=0xbfffed3c) at
main.m:42
#9  0x40583091 in __libc_start_main (main=0x804c3e0 <main>, argc=1,
    ubp_av=0xbfffed34, init=0x804c100 <_init>, fini=0x80afc30 <_fini>,
    rtld_fini=0x4000e374 <_dl_fini>, stack_end=0xbfffed2c)
    at ../sysdeps/generic/libc-start.c:129

P.S.
I've *not* changed this part of the code from about a year ;-)