1 files changed, 21 insertions, 15 deletions

diff --git a/lwlib/lwlib-Xm.c b/lwlib/lwlib-Xm.c
index b33a53e43fc..4a3f097a867 100644
--- a/lwlib/lwlib-Xm.c
+++ b/lwlib/lwlib-Xm.c
@@ -265,26 +265,32 @@ xm_arm_callback (w, client_data, call_data)
   widget_value *wv = (widget_value *) client_data;
   widget_instance *instance;
 
-  /* Get the id of the menu bar or popup menu this widget is in.  */
-  while (1)
+  /* During the pretest of 21.1, there was a case where this callback
+     was called with a null widget on hpux 10.2.  I think that's
+     likely a bug in the Motif lib there.  */
+  if (w != None)
     {
-      if (XmIsRowColumn (w))
+      /* Get the id of the menu bar or popup menu this widget is in.  */
+      while (1)
         {
-          unsigned char type = 0xff;
+          if (XmIsRowColumn (w))
+            {
+              unsigned char type = 0xff;
 
-          XtVaGetValues (w, XmNrowColumnType, &type, NULL);
-          if (type == XmMENU_BAR || type == XmMENU_POPUP)
-            break;
-        }
+              XtVaGetValues (w, XmNrowColumnType, &type, NULL);
+              if (type == XmMENU_BAR || type == XmMENU_POPUP)
+                break;
+            }
 
-      w = XtParent (w);
-    }
+          w = XtParent (w);
+        }
 
-  instance = lw_get_widget_instance (w);
-  if (instance && instance->info->highlight_cb)
-    {
-      call_data = cbs->reason == XmCR_DISARM ? NULL : wv;
-      instance->info->highlight_cb (w, instance->info->id, call_data);
+      instance = lw_get_widget_instance (w);
+      if (instance && instance->info->highlight_cb)
+        {
+          call_data = cbs->reason == XmCR_DISARM ? NULL : wv;
+          instance->info->highlight_cb (w, instance->info->id, call_data);
+        }
     }
 }