Well, the issue is that I need no URLs at all to be altered.  This includes entering them via forms or typing them by hand in the HTML view.  So when I have "Default" which is supposed to not convert URLs, I'm not expecting an input form for INPUT to append or change the Src url when I switch tabs.

 

This is because the users that are going to be using my control will be entering in SiteRelative and Absolute paths.  I need to allow them to be able to do that which for the most part works with it set to "Default" except for the mentioned form.