It can be both a blessing and a curse to have so many options when choosing a GUI for your Ruby application. Ultimately, there is no magic formula to make this decision for you, but here are a few considerations to keep in mind:

• Upon which platforms will your application need to run? If you need support for the Macintosh, Tk is really your only choice at this time. Similarly, if you need to support platforms other than Microsoft Windows, you probably don't want to develop the GUI using SWin/VRuby.

• If you do intend for your application to run on different platforms, do you prefer a uniform look-and-feel for the GUI, or would you rather have a native look-and-feel for each target platform? Tk provides a native look-and-feel on each platform, but "theme-able" toolkits like GTK can provide extremely customizable interfaces (possibly different from any platform's native GUI). FOX provides a consistent look-and-feel for both Unix and Windows (but that look-and-feel is decidedly Windows-like).

• Software licensing issues can be a significant concern, especially if you're developing commercial software applications. Most of the GUI toolkits for Ruby use some kind of open-source software license, but you should study their licenses carefully to understand the terms.

All other issues aside, the great intangible factor is how comfortable you are developing programs with a given toolkit. From a programmer's standpoint, every GUI toolkit has its own unique character and feel and you may not be able to put a...