Ok, now back to the original problem. When I type something in the edtNotes and then press Open button (this button is next in Tab sequence), the typed value in editbox miraculously disappear. That was the orginal problem the QA person came to me and I just fixed another one I've noticed.

But this problem is still hapenning and setting SET STEP ON in the Lostfocus of Editbox in question doesn't explain the mystery.