<p>Modern browsers have multi-tab interface, but JavaScript function <code>window.showModalDialog()</code> creates a modal dialog that blocks <em>all</em> of the tabs.  </p>

<p>I'd like to know if there is a way to create a modal dialog that blocks only the tab it's been created in?</p>

You could use one of the more 'Ajax-like' modal dialogs, which are just absolute positioned divs, floating on top of everything else.
Those are modal to the 'document' and not the browser.
For instance take a look it
this jQuery plugin
P.S.
```
showModalDialog()
```
is an IE only call, so you might want to not use that altogether.