The short version, this mod will correct the aspect ratio of the Quake 3 interface to work with any wide screen graphics mode.
Why is this even needed? Well, when Quake 3 Arena was originally released everyone had CRT monitors with a 4:3 aspect. Most people ran Quake 3 at either 640x480 or 800x600 screen size. These days a 16:9 or even 16:10 aspect ratio is the most common and the default for Quake 3 is to stretch the interface to match the new size.
Simply disabling that stretch is not a default option, but ZTM's Flexible HUD solves this issue.
Another great feature is the display of 8 maps instead of 4 in the map menu selection.
There are also a number of new cvars to make sure you get everything set-up just the way you want. Be sure to check the authors site for a lot more details. As expected, the source code is available as well.
And while you are correcting the aspect ratio issue on your nice widescreen monitor, be sure to check out [HQQ] High Quality Quake which will improve the crispness of the menu graphics. These two mods complement each other nicely.
Review by Tig