PHP FFI vector by reference

Question

In PHP 4.4.4 (bamcompiler to be more precise) I try to use w32api FFI to interface with iup GUI library like this:

<?
$iup=new win32;
$iup->registerfunction("int IupOpen (int argc,string argv) From iup.dll");
$iup->registerfunction("int IupClose () From iup.dll");
$iup->registerfunction("int IupMainLoop () From iup.dll");
$iup->registerfunction("long IupDialog (long child) From iup.dll");
$iup->registerfunction("int IupShow (long child) From iup.dll");
$iup->registerfunction("long IupHboxv (long &child) From iup.dll");
$iup->registerfunction("long IupLabel (string title) From iup.dll");
$iup->registerfunction("long IupButton (string title,string action) From iup.dll");
$iup->registerfunction("long IupSetAttributes (long ih,string attrs) From iup.dll");
$iup->IupOpen(null,null);
$b=$iup->IupButton("vasile","apasa");
$l=$iup->IupLabel("asta e vasile");
$hbc=pack("L*x",$l,$b);
$hb=$iup->IupHboxv(&$hbc);
$dia=$iup->IupDialog($hb);
$iup->IupSetAttributes($dia,"SIZE=300x200");
$iup->IupShow($dia);
$iup->IupMainLoop();
$iup->IupClose();
?>

and all I get is an empty window.

If I give the address of one of the controls to IupHboxv ex:(&$b), I get that control in the window, so I think it have something to do with the address of the packed string.

The w32api is too thin and for the pack function I've read the Perl docs.