[win32] Memory corruption with certain preferences.xml

[Liam P. White]

Insert attached into %appdata%\inkscape\preferences.xml, overwriting the old file if necessary. Then launch inkscape.exe with gdb (I don't think it matters if you have debug symbols or not).

Shortly after startup, the Inkscape window will begin to load. However, gdb will stop execution right there with a SIGTRAP, and the window will not finish loading. In fact, there will be several hundred traps.

gdb doesn't give good backtraces about this, but Visual Studio 2012 had symbols for ntdll and could debug a little bit.

#0 ntdll.dll!RtlpBreakPointHeap ()
    0x7702F0C1 int 3
#1 ntdll.dll!RtlpAllocateHeap ()
#2 ntdll.dll!RtlAllocateHeap ()
#3 ntdll.dll!RtlDebugAllocateHeap ()
#4 ntdll.dll!string "Enabling heap debug options\n" ()
...etc.

(the x86 instruction "int 3" is a trap to the debugger)

Console output with gdb is several thousand of these:
warning: heap block 0x0000HHHH modified after it was freed

To ignore the traps, I have either:

1. deleted preferences.xml
2. (gdb) handle SIGTRAP noprint nostop nopass

(this also happens with special 64-bit Inkscape compiled with MSYS)