Firefox Showcase is an interesting add-on that displays your open windows and tabs in one collected view with many options, including window, sidebar, and scroll bar views. In fact, you can customize most aspects of this free extension.
We installed Showcase, restarted Firefox, and opened some Web sites in several tabs. We clicked the small menu arrow next to Firefox's Add Tab button, and Showcase's window view opened with all our opened tabs displayed as large thumbnails. We could also open and view new Firefox windows as well as tabs, and later learned we could set Showcase to show just one or the other. We clicked View/Sidebars and selected Showcase Sidebar (we could also select Showcase All Windows Sidebar), which opened the sidebar with all our Firefox windows displayed in a scrolling view. There is also a Showcase menu in View, which let us open the window and tab views as well as access the Showcase options; these options are also available via the add-on manager. And what extensive choices the options dialog offers, with entries for configuring the Window, Tab, Sidebar, Thumbnails, Shortcuts, and Advanced Options. Many entries have multiple tabs; for instance, the Windows settings has tabs labeled General and Attributes that let us configure the size of the thumbnails, the background color, the scroll bar orientation, and the width, height, and position of the window. The Showcase Web site offers many tips and tricks in addition to a manual, screenshots, Changelog, and other support; it's accessible via the program's add-ons manager page.
While Showcase proved compatible with Firefox 4.0.1, the Showcase menu entries didn't show up in the new-style interface that doesn't display the Menu Bar. The keyboard shortcuts worked fine, though, and you can either use them to invoke Showcase's various modes or simply opt to show the Menu Bar by clicking View/Toolbars and selecting the Menu Bar's check box.