DT Pro 2: Applescript difficulties with retrieving URL

I have an old script which copies a selected text, adds the URL of the document and opens Mail so that I can paste this information there and send it via email.

Now it seems to have some trouble in retrieving the URL in DT Pro 2. Here is an adapted short version with the lines which don’t work.

tell application id "com.devon-technologies.thinkpro2"
	set this_url to the URL of think window 1
	display dialog this_url
end tell

this_url is alway empty. What’s wrong here?

Thanks for any help in getting the URL,

The URL of think windows is the one of eventually visible web views. To get the URL of the visible document, use…

set this_url to the URL of content record of think window 1