"To move a tab to its own window, click on the tab and drag it below the tab strip. Or, to move a tab from one Firefox window to another, click on the tab and drag it to the tab strip of another Firefox window." is how it's supposed to work but instead, the "new" window disappears and is gone. I can see in the Window drop-down menu that Firefox thinks it has the new window open someplace, but it's completely unselectable and just plain gone. I have disabled any add-ons and even deleted and re-installed the browser and it still happens.