macOS I have a new Mail message window opened. How to set it's Subject via Applescript?

Hi,

All the examples I've found create a new message then set it's subject via applescript like this:

set newMessage to make new outgoing message with properties {account:theAccount, subject:theSubject, content:theContent}

However I'm looking for a way to set the Subject and Recipient of an existing message in the frontmost window, like this:

http://cl.ly/image/2Z0u0M0J050R

Is it possible?

Thank you.

found the solution: ui scripting.