I have another bug to submit.
Let's suppose I have as current date 2019/08/01. Shown deltaT is 69,80279 seconds. If I change the year from 2019 to 1900 deltaT value is the same, even though I take the focus out of the year text box. DeltaT is updated only if I switch off and on the Automatic DeltaT Calculation check box. In this case it is correctly shown as -1.995301 seconds.