Contacting the Win32::GUI maintainer seems somewhat difficult, so would an XS hacker please set me straight? As this post also contains a, cough, "fix", others might find this useful.

Issue is this: the Win32::GUI TreeView->InsertItem() method works correctly on 32bit perl but does not on 64bit perl (this is Win32::GUI 1.12 under Strawberry 5.22.1 on Win7).

Run this code on both perl versions and compare the order of items in the tree (or run on x64 only and be baffled):

use strict;
use Win32::GUI;

sub TVI_FIRST { 0xFFFF0001 }

my $Window = new Win32::GUI::Window(
    -name   => "Window",
    -text   => "Win32::GUI v. $Win32::GUI::VERSION TreeView: 32bit vs.
+ 64bit",
    -height => 200, 
    -width  => 350,
    -left   => 100, 
    -top    => 100,
);

my $TV = $Window->AddTreeView(
    -width     => $Window->ScaleWidth, 
    -height    => $Window->ScaleHeight,
    -left      => 0, 
    -top       => 0,
    -lines     => 1, 
    -rootlines => 1,
    -buttons   => 1
);

my $rootNode = $TV->InsertItem(
    -text          => "rootNode", 
);

my $childNode = $TV->InsertItem(
    -parent        => $rootNode, 
    -text          => "childNode", 
    -item          => TVI_FIRST
);

my $childAtt2 = $TV->InsertItem(
    -parent        => $childNode, 
    -text          => "childAtt2", 
    -item          => TVI_FIRST
);

my $childAtt1 = $TV->InsertItem(
    -parent        => $childNode, 
    -text          => "childAtt1", 
    -item          => TVI_FIRST
);

# root attribute inserted _after_ inserting child nodes, but should
# display _before_ child nodes

my $rootAtt1 = $TV->InsertItem(
    -parent        => $rootNode, 
    -text          => "rootAtt1", 
    -item          => TVI_FIRST  
);

$TV->Expand($_) for($rootNode, $childNode);
$Window->Show();
Win32::GUI::Dialog();
# eof
[download]

Since this is a bitness issue, my hunch is that it must be related to pointers. I think I tracked this down as far as GUI_Helpers.cpp::handle_From() where the conversion of integers to pointers for InsertItem() takes place.

I "fixed" the issue in the definiton of InsertItem() in TreeView.xs by replacing line 815

  Insert.hInsertAfter = (HTREEITEM) handle_From(NOTXSCALL ST(next_i));
[download]

with

  switch(SvIV(ST(next_i))){

  case 0xFFFF0001:
    Insert.hInsertAfter = TVI_FIRST;
    break;
    
  case 0xFFFF0002:
    Insert.hInsertAfter = TVI_LAST;
    break;

  case 0xFFFF0003:
    Insert.hInsertAfter = TVI_SORT;
    break;

  default:
    Insert.hInsertAfter = (HTREEITEM) handle_From(NOTXSCALL ST(next_i)
+);
    break;
  }
[download]

This looks pretty awful, even to me as a non-XS hacker.

So my question: what is the underlying problem and how is it fixed properly?