Good news, build UltraExplorer 2.5 OK and it runs.
Immediately found the bug that has stopped me running 2.0.3.1 on my main development PC for a year, if UltraOptions.cfg is blank you get a silly start-up error without that filename being mentioned.
Now just need to go back and try and put back code I commented out, party it seems because defines in project options and include files are sometimes ignored so certain code never gets built. Then I'll make it all more widely available, somehow.
Angus