emacs-21.1.94 crash in gnus on Windows

[Andy Moreton <andrewjmoreton@gmail.com>]

Hi,

I've built 21.1.94 pretest on WinXP SP3 with MinGW gcc, and I'm seeing
a repeatable crash in gnus. Running emacs under gdb I managed to capture
a crash, with the following results:

Program received signal SIGSEGV, Segmentation fault.
0x0102ef33 in pos_visible_p (w=0x2fa6e00, charpos=0x22fa, x=0x82eef8, y=0x82eef4, rtop=0x82ef08,
    rbot=0x82ef04, rowh=0x82ef00, vpos=0x82eefc) at xdisp.c:1397
1397                             && (!BUFFERP (glyph->object)
(gdb) warning: frame 02FA6400 (emacs@aji *Group*) obscured

warning: obscured frame 02FA6400 (emacs@aji *Group*) found to be visible

bt
#0  0x0102ef33 in pos_visible_p (w=0x2fa6e00, charpos=0x22fa, x=0x82eef8, y=0x82eef4,
    rtop=0x82ef08, rbot=0x82ef04, rowh=0x82ef00, vpos=0x82eefc) at xdisp.c:1397
#1  0x010f62d8 in Fpos_visible_in_window_p (pos=0x8be8, window=0x2fa6e05, partially=0x2ba7802)
    at window.c:357
#2  0x010228b1 in Ffuncall (nargs=0x3, args=0x82f010) at eval.c:3030
#3  0x01113471 in Fbyte_code (bytestr=0x3904201, vector=0x3aacc05, maxdepth=0x10) at bytecode.c:680
#4  0x01022fae in funcall_lambda (fun=0x3ab08c5, nargs=0x0, arg_vector=0x82f2c8) at eval.c:3211
#5  0x01022a86 in Ffuncall (nargs=0x1, args=0x82f2c4) at eval.c:3070
#6  0x01113471 in Fbyte_code (bytestr=0x39182e1, vector=0x3aac405, maxdepth=0x10) at bytecode.c:680
#7  0x01022fae in funcall_lambda (fun=0x3ab6125, nargs=0x1, arg_vector=0x82f574) at eval.c:3211
#8  0x01022a86 in Ffuncall (nargs=0x2, args=0x82f570) at eval.c:3070
#9  0x01113471 in Fbyte_code (bytestr=0x3ab7831, vector=0x3abad05, maxdepth=0x14) at bytecode.c:680
#10 0x01022fae in funcall_lambda (fun=0x3abbae5, nargs=0x1, arg_vector=0x82f884) at eval.c:3211
#11 0x01022a86 in Ffuncall (nargs=0x2, args=0x82f880) at eval.c:3070
#12 0x01117b8a in Fcall_interactively (function=0x3a6f6d2, record_flag=0x2ba7802, keys=0x2bacb05)
    at callint.c:869
#13 0x010228b1 in Ffuncall (nargs=0x4, args=0x82fb50) at eval.c:3030
#14 0x0102244f in call3 (fn=0x2bcc5ca, arg1=0x3a6f6d2, arg2=0x2ba7802, arg3=0x2ba7802)
    at eval.c:2850
#15 0x01014d20 in Fcommand_execute (cmd=0x3a6f6d2, record_flag=0x2ba7802, keys=0x2ba7802,
    special=0x2ba7802) at keyboard.c:10507
#16 0x010076b0 in command_loop_1 () at keyboard.c:1904
#17 0x01020549 in internal_condition_case (bfun=0x100625a <command_loop_1>, handlers=0x2bb54da,
    hfun=0x1005c3b <cmd_error>) at eval.c:1490
#18 0x01005fb3 in command_loop_2 () at keyboard.c:1360
#19 0x0102009a in internal_catch (tag=0x2bb51b2, func=0x1005f8e <command_loop_2>, arg=0x2ba7802)
    at eval.c:1226
#20 0x01005f6c in command_loop () at keyboard.c:1339
#21 0x0100585e in recursive_edit_1 () at keyboard.c:954
#22 0x010059c7 in Frecursive_edit () at keyboard.c:1016
#23 0x010028c5 in main (argc=0x1, argv=0xa44418) at emacs.c:1833

Lisp Backtrace:
"pos-visible-in-window-p" (0x82f014)
"gnus-summary-recenter" (0x82f2c8)
"gnus-summary-display-article" (0x82f574)
"gnus-summary-next-page" (0x82f884)
"call-interactively" (0x82fb54)
(gdb)

Please let me know what other info/testing is needed to help fix this.

    AndyM