Changing trigger condition doesn't work

When I change trigger condition, it does nothing

How to reproduce

1. CLick RMB on some trigger, select properties
2. Select tab definition
3. Into "Where" field enter enything
4. Select tab SQL
5 SQL preview is empty

I noticed it while trying to remove existing condition, so it doesn't
work for sure.
I checked Adding/changing by only looking at SQL preview field.

MK