Wipe - How to - Help needed

If anyone has a thread they could point me to or a possible direction I could go in with TGB. I am attaching an image to help explain the scripting problem I am having. I am looking to "wipe" pixels of an image map or some other type of screen object in the manner portrayed in the image attached.

Is this possible in TGB?

Thank you for any advice.

<img src="http://www.mongadillo.com/Private/example_wipe.jpg">