The [Un]read extension provides a button for easy switching between "view all" and "view unread" message filters.
In addition, this extension automatically switches to the "view all" mode when you start typing in the search box while in "view unread" mode. This makes it easier to find messages that may have been missed.
Requirements for using the [Un]read extension include having Thunderbird 1.5 - 1.5.0.* installed on your system.
This latest release of the extension also includes a new feature where if you have typed something in the search box and then click the [Un]read button, the search will be automatically cleared. This makes the user experience smoother and more seamless.
Overall, the [Un]read extension is a great addition to Thunderbird that streamlines message filtering and search processes for users.