Updated use of zap_gadget to avoid memory overwrite problem.

c/create

@@ -138,12 +138,13 @@ extern _kernel_oserror *create_object (_kernel_swi_regs *r, TaskDescriptor *t,in
 
    if (dcs_template->message) {
       zap_gadget(template,Button,Message_Gadget,value,dcs_template->message);
+      temp = 1+string_length(dcs_template->message);
    } else {
       /* len = maximum (len,template_length) */
       temp = *(read_gadget(template,Button,Message_Gadget,max_value));
-      if (temp > len) len = temp;
    }
 
+   if (temp > len) len = temp;
    zap_gadget(template,Button,Message_Gadget,max_value,len);
 
    if ((er=create_from_template(template, &new->window)) != NULL)  goto error;