Nadya,
>Should I call thisform.refresh or it would be enough to call thisform.txtMsg.refresh()?You can .Refresh() just the textbox, you can encapsulate everything in a method call.
>The strange thing is, that it worked fine before without refresh(). Also if I click once on this control, all other messages are updated correctly during the execution of the form...because the textbox has focus it'll update on the screen whenever the .Value changes.