1. Ok, to see expected behavior, open the link below in a new window. The page loaded there will have a "Find Foo" button; click it. That just runs a script that grabs a handle to this window and displays it with alert().

2. Now, to see the bug, open the link below in a new tab, instead of a new window. That will put this window into a background tab. Then click the "Find Foo" button again. Instead of finding this window, it opens a brand new window with no content (about:blank?).

3. You can see the bug manifested again if you open another tab (to your home page, or wherever -- it doesn't matter) alongside this window, and open the link below into a new window. Then come back to this window, and click on the other tab (the one that's at your home page, or wherever), so that this window's tab is put into the background. Then switch back to the newly opened window, and click the "Find Foo" button again; another new window with no content will appear.

4. And, finally, to see it work right again, set things up as in example 3 again: this window in one tab, your home page in another tab, and the link below opened in a new window. But this time, leave this page as the tab being displayed, and the tab with your home page in it backgrounded. Then, when you click the "Find Foo" button, no new window will be opened.

[The Link]