The Desktop extension, besides the fact that it offers you a quick method to change your background image also provides you full control on the images layout.
NOTE: The Desktop add-on is cross-platform and it works on Mac OS X, Windows and Linux.
Here are some key features of "Desktop":
· Add thumbnails to new tabs
· Align them by drag&drop
· Create sub-folders
· Sync layout using extensions like XMarks or Weave
· Firefox 3.0b5 to 4.0b9pre
What`s New in This Release: [ read full changelog ]
· Max version updated to Firefox 4.0b9pre, ability to stretch background and some bugfixes.