Personally, I've found the C parser of Win32::API something I don't rely on - it's a recent addition and did not seem to work in all cases. I prefer using the "pack"-style parameter templates:

use strict;
use Win32::API;

my $gl_getstring = Win32::API->new('OpenGL32', 'glGetString', 'I', 'P'
+);
die "Could not load glGetString : $! / $^E"
  unless $gl_getstring;

print "Vendor(a): ", unpack "p", $gl_getstring->Call(0x1F00);
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I can't test this on my system, as both your variant and my variant seem to crash somewhere, and I don't know how this system here is set up/crippled. You need to change the library to OpenGL32 though, as that's the name of the library on Win32.

I just noticed - I had to change your call some more, before Win32::API accepted it at all:

my $gl_vendor = Win32::API->new(
    "OpenGL32", "char* glGetString(int a)"
)->Call( 0x1F00 );
print "Vendor (b): ", $gl_vendor;
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I've done some work with OpenGL::Simple and have had relatively good success with it, but I haven't delved into the depths of OpenGL programming. If you want/need a test account, I can make you the same offer I already made to Michael Schwern, that you can mail me files that get run on my Win32 machine (when it's on). My personal interest in SDL is limited though, so I won't be working on it.