Thunderbird is a total redesign of the Mozilla mail component to produce a cross-platform, stand-alone mail application using the XUL user interface language. It has many new features, among them the ability to customize your toolbars the way you want them. a new look and feel with a large number of downloadable themes which alter the appearance of the client, and the ability to add UI extensions.
The "fmconv" script modifies the /etc/fstab file and the /boot/grub/menu.lst file to use either UUID strings or device filenames depending upon the parameter settings (-u or -d). This easy conversion to device filenames for maintenance purposes (UUID strings are hard to maintain, and just annoying), and the conversion back to UUID strings allows grub to work in an environment where the boot disk sequence is poorly defined by the BIOS. The original files are never overwritten.