(x_set_icon_name): Don't use arg if it's not a string and not nil.

src/ChangeLog

+2006-06-03  Eli Zaretskii  <eliz@gnu.org>
+
+	* w32fns.c (x_set_icon_name): Don't use arg if it's not a string
+	and not nil.
+
 2006-06-02  Chong Yidong  <cyd@stupidchicken.com>
 
 	* xfns.c (x_set_icon_name): No-op if arg is non-nil and not a

src/w32fns.c

@@ -1683,7 +1683,7 @@ x_set_icon_name (f, arg, oldval)
       if (STRINGP (oldval) && EQ (Fstring_equal (oldval, arg), Qt))
 	return;
     }
-  else if (!STRINGP (oldval) && EQ (oldval, Qnil) == EQ (arg, Qnil))
+  else if (!NILP (arg) || NILP (oldval))
     return;
 
   f->icon_name = arg;