Oops, WaitNextEvent was hand-coded, and it also needed the h->H conversion for PyArg_ParseTuple format strings.
diff --git a/Mac/Modules/evt/Evtmodule.c b/Mac/Modules/evt/Evtmodule.c
index 093c470..c161c75 100644
--- a/Mac/Modules/evt/Evtmodule.c
+++ b/Mac/Modules/evt/Evtmodule.c
@@ -328,7 +328,7 @@
UInt32 sleep;
Handle mouseregion = (Handle)0;
- if (!PyArg_ParseTuple(_args, "hl|O&",
+ if (!PyArg_ParseTuple(_args, "Hl|O&",
&eventMask,
&sleep,
OptResObj_Convert, &mouseregion))
diff --git a/Mac/Modules/evt/evtsupport.py b/Mac/Modules/evt/evtsupport.py
index d4fb595..7725ded 100644
--- a/Mac/Modules/evt/evtsupport.py
+++ b/Mac/Modules/evt/evtsupport.py
@@ -79,7 +79,7 @@
UInt32 sleep;
Handle mouseregion = (Handle)0;
-if (!PyArg_ParseTuple(_args, "hl|O&",
+if (!PyArg_ParseTuple(_args, "Hl|O&",
&eventMask,
&sleep,
OptResObj_Convert, &mouseregion))