r3886で発生するのを確認しました。
r3870では発生しませんでした。
(以前も一時、発生していたような、、、)
以下にMingwのgdbでとったbacktraceをつけます。
Program received signal SIGTRAP, Trace/breakpoint trap.
[Switching to thread 5636.0xd20]
0x7c941231 in ntdll!DbgUiConnectToDbg () from ntdll.dll
(gdb) bt
#0 0x7c941231 in ntdll!DbgUiConnectToDbg () from ntdll.dll
#1 0x011465ab in w32_abort () at mw32fns.c:4852
#2 0x01153ada in mw32_fill_area_pix (f=0x224e600, pix=16777215, x0=9, y0=113,
x1=17, y1=129) at mw32term.c:463
#3 0x01153b9f in mw32_clear_frame_area (f=0x224e600, x=9, y=113, width=8,
height=16) at mw32term.c:493
#4 0x0103872f in erase_phys_cursor (w=0x28c1a00) at xdisp.c:20955
#5 0x01038bc2 in display_and_set_cursor (w=0x28c1a00, on=1, hpos=0, vpos=4,
x=0, y=64) at xdisp.c:21043
#6 0x01038eb8 in update_window_cursor (w=0x7c95056d, on=8652296)
at xdisp.c:21082
#7 0x00000001 in ?? ()
#8 0x00000000 in ?? () from
#9 0x00000004 in ?? ()
#10 0x00000000 in ?? () from
#11 0x00000040 in ?? ()
#12 0x111b772c in ?? ()
#13 0x01038f10 in update_cursor_in_window_tree (w=0x224e600, on_p=42736128)
at xdisp.c:21104
#14 0x00000000 in ?? () from
#15 0x111b774c in ?? ()
#16 0x01157629 in mw32_frame_rehighlight_1 (dpyinfo=0x224e600)
at mw32term.c:2678
Previous frame inner to this frame (corrupt stack?)
(gdb)
