Changing bbcode behavior?

[Tamorlane]

Perhaps I am searching for the wrong thing, or perhaps it is so painfully simple that no one ever asked. Bear with a new VBB user....

In the editor there is a button for inserting an image link. This button launches a window wherin the user places the url. I have seen this button work differently on some VBB's, in so far as the user would highlight the url in the post body, click the IMG button, and the editor would wrap the highlighted URL with the IMG tags.

Is there a way to modify the behavior of the IMG button in the editor to do this, or would a custom BBcode need to be created?

Thanks.