[Bug 20313] New: Patch "user32: Draw the whole button only if requested" caused uninitialized memory use

http://bugs.winehq.org/show_bug.cgi?id=20313

Summary: Patch "user32: Draw the whole button only if
                    requested" caused uninitialized memory use
           Product: Wine
           Version: 1.1.27
          Platform: PC
               URL: http://source.winehq.org/git/wine.git/?a=commit;h=8d54
                    f582776d590b236e288f9ef8085bb221ccab
        OS/Version: Linux
            Status: NEW
          Keywords: download, regression, source
          Severity: normal
          Priority: P2
         Component: user32
        AssignedTo: [e-mail]
        ReportedBy: [e-mail]
                CC: [e-mail]

Running the ntdll tests under valgrind, I get a crash.
Because I also happen to have visual studio 2005 installed,
I got a handy crash dialog offering to debug.
That dialog seemed to cause the following valgrind error:

Conditional jump or move depends on uninitialised value(s)
   at IsRectEmpty (uitools.c:1282)
   by IntersectRect (uitools.c:1331)
   by PB_Paint (button.c:880)
   by paint_button (button.c:207)
   by ButtonWndProc_common (button.c:450)
   by ButtonWndProcW (button.c:564)
   ...
   by SetFocus (focus.c:293)
   by ButtonWndProc_common (button.c:336)
   by ButtonWndProcW (button.c:564)
   ...
 Uninitialised value was created by a stack allocation
   at PB_Paint (button.c:802)

Either adding the line
   memset(&focus_rect, 0, sizeof(focus_rect));
at the top of PB_Paint, or reverting the patch
http://source.winehq.org/git/wine.git/?a=commit;h=8d54f582776d590b236e288f9e...
makes the warning go away.  Evidently that patch
jumped over the initialization of that variable
when it shouldn't have...