Hi Marco, Fillets and other commands that might have a long execution time have a special asynchronous factory where the work for them is still done in a separate process called moi_commandprocessor.exe . When a command like that is running, it should still be cancelable, the work for the fillet calculation itself is not happening on the main thread even in v4, only the script logic is running on the main thread in v4. The difference from v3 is that in v3 both the script code and async factories were running in a 2 different instances of moi_commandprocessor.exe , in v4 it's only the async factories that are doing that.

I just tested over here and I can't reproduce an uncancelable fillet, I'd need to get an example file that demonstrates the problem in order to find out any more about what's going on.

- Michael