Question: Can TextMate be changed to "shift text to right" by highlighting text and pressing Tab?

Right now it actually replace the whole selected text with a tab character but I almost never want to do something like that. I think some other editors like Notepad++ will indent to the next level.

Answer: 
Sub-domains are considered different and will fail the [Same Origin Policy](http://en.wikipedia.org/wiki/Same_origin_policy) unless both sub-domains declare the same `document.domain` DOM property (and even then, different browsers behave differently).
Short answer: No. See the [Same Origin Policy](https://developer.mozilla.org/en/Same_origin_policy_for_JavaScript)

You can only make an XHR request to the same host, port, and protocol. 

If you want to do Ajax without sticking to that, you can look at [JSON-P](http://remysharp.com/2007/10/08/what-is-jsonp/).

(XSS is a completely different kettle of fish, in which a site allows data to be injected into it (e.g. via a URI) that gets treated as JS allowing third parties to direct people to your site, while they are logged into it, and steal or edit data.)