s/ARB/MESA/ in extension check (bug 10126)
diff --git a/progs/demos/winpos.c b/progs/demos/winpos.c
index 2ee1df6..3a1a19e 100644
--- a/progs/demos/winpos.c
+++ b/progs/demos/winpos.c
@@ -77,7 +77,7 @@
       WindowPosFunc = &glWindowPos2fARB;
    }
    else
-#elif defined(GL_ARB_window_pos)
+#elif defined(GL_MESA_window_pos)
    if (glutExtensionSupported("GL_MESA_window_pos")) {
       printf("Using GL_MESA_window_pos\n");
       WindowPosFunc = &glWindowPos2fMESA;