If you give access to the parent frame, when an error condition has occured and you
want to terminate it, then when will you know when the user is done scrolling your
log panel(JTextArea)?

Wouldn't it be easier, from a usability perspective as well, to present the log on the error
dialog --say have a tabbed pane in the dialog with two tabs, one with the error message,
and the other one with a copy of the JTextArea?

Then users will be able to inspect what has happened, and when they confirm that they are done
with the dialog, you can also terminate your application.

I think this is what we tend to see, and is much more usable, and much easier to implement.

Best regards

George T