Internet Explorer has a well known proprietary modal dialog window that can be opened using showModalDialog DOM command. While it is not a good idea to use browser-specific functionality, for many it’s a convenient way to display a modal window and return result back to the parent.
But there is an easy fix for that. If you include following line:
inside of your page header in HTML source, e.g.:
<head> <title>My Page</title> <base target="_self"></base> </head>
modal dialog will be able to successfully postback to itself.