Apparently recently a feature was added so that tabs created by a redirected window.open or the like behave differently than normal tabs, in that closing them switches the current tab back to the originating page rather than the next tab in the tab order. This seems like a bad idea, as it means tabs will act differently with no indicator to the user that this is going to happen. If someone doesn't remember how a tab was created and starts to close a number of open tabs (repeated clicking on a single close button or repeated keyboard shortcut), they'll get rudely suprised when tabs they didn't expect are closed because the traversed order is different from the visual representation. Offhand it seems the best solution for this might be to have the redirected window open tabs be inserted in the tab order after the current tab instead of at the end.

This was discussed at length in several other bugs (bug 262459, bug 327562 are two) and in the dev.apps.firefox newsgroup. See also tracker bug 345028. This should probably be duped to that.

bug 465673 solves this per reporter's suggestion in last paragraph of comment #0

Thanks Eyal. This is indeed be fixed by bug 465673 now.