Convincing Valgrind to give a stack dump?

[Dan Kegel]

Looking at the app in bug 10125, using warn+heap, I saw
a few of those scary-but-sometimes-harmless warnings,
so I thought I'd give it a shot under Valgrind.  After applying
enough suppressions, I did find three interesting valgrind
warnings:

 10 errors in context 5 of 9:
 Conditional jump or move depends on uninitialised value(s)
    at 0x477F7F6: RedrawWindow (painting.c:612)

 29 errors in context 7 of 9:
 Conditional jump or move depends on uninitialised value(s)
    at 0x43E4E6D: HEAP_ValidateInUseArena (heap.c:917)

 184 errors in context 9 of 9:
 Conditional jump or move depends on uninitialised value(s)
    at 0x61F3CD0: XcursorImageHash (in /usr/lib/libXcursor.so.1.0.2)

The commandline I used was
WINEDEBUG=+process valgrind -v --error-limit=no --trace-children=yes
--suppressions=$HOME/suppressions ~/wine-git/wine Olb.exe

(+process was used to show that the errors in question did
indeed come from olb.exe and not something it launched.)

But I couldn't coax Valgrind into giving stack dumps for those errors;
it acted as if it had seen a few too many errors first, and only
showed the one line.  Grr.  Anyone know how to coax valgrind
into always giving a good stack dump?
- Dan