I realize that this is rather an old thread. Nevertheless, I'd like to share a little program that I've made recently, which can help you achieve the described goal. How it works: Simply speaking SymlinkSwapper creates a file (symbolic link/symlink), which you can use as a sensor panel background. Symlink points to one of the files in the directory of your choosing. After user-defined time passes, SymlinkSwapper replaces the file it created with a new symlink, this time pointing to