pthread_t can well be a 64-bit value -- on FreeBSD/amd64, for example.
Better to just keep calling it pthread_t isntead of casting to anything.

	-mi

--- ../pr/include/private/pprthred.h	Sun Apr 25 11:00:56 2004
+++ ../pr/include/private/pprthred.h	Tue Jul 12 00:52:42 2005
@@ -44,4 +44,5 @@
 */
 #include "nspr.h"
+#include <pthread.h>
 
 #if defined(XP_OS2)
@@ -92,5 +92,5 @@
 ** when it is created or attached.
 */
-NSPR_API(PRUint32) PR_GetThreadID(PRThread *thread);
+NSPR_API(pthread_t) PR_GetThreadID(PRThread *thread);
 
 /*
--- ../pr/src/pthreads/ptthread.c	Wed May 25 22:27:51 2005
+++ ../pr/src/pthreads/ptthread.c	Tue Jul 12 00:49:50 2005
@@ -979,10 +979,10 @@
 }
 
-PR_IMPLEMENT(PRUint32) PR_GetThreadID(PRThread *thred)
+PR_IMPLEMENT(pthread_t) PR_GetThreadID(PRThread *thred)
 {
 #if defined(_PR_DCETHREADS)
     return (PRUint32)&thred->id;  /* this is really a sham! */
 #else
-    return (PRUint32)thred->id;  /* and I don't know what they will do with it */
+    return thred->id;  /* and I don't know what they will do with it */
 #endif
 }