Carl,
I tried the following befor re-importing the “window”:
1.) restarted the designer
2.) restarted the modules on the gateway PC
3.) restarted the entire gateway PC service
4.) Cleared Java Cache (Client PC) - including removing apps (using Java Control panel)
5.) backed up the project & restored to a different gateway (trial version on local PC)
None of which worked, hence the “Delete” & re-import of that window.
(I have a copy of the project including the corrupted window If it would be of any help)
Peter