The matter is same: too many calculation because of loop. Sometimes the error
message is displayed but sometimes the calculation fields are just zero
without warning. I received advice to do boolean flag as follows

var handler = 0;
function ...::OnAfterChange(eventObj)
{
  if(eventObj.IsUndoRedo || handler > 0) return;
  handler = 1;
....

 handler = 0;
}

I just can't get it work or I can't use it properly. Programming skill is
not so good. Big amount of calculation should be launched when opening the
form and excuting a query from database(XDocument.Query();). Also
calculations should be made when certain check box is checked. I have
problems in both cases. At least one of those cases is not working when
executing. What can be done?

Sorry if I have asked similar questions, but I just want to make this work
properly.