When Tornado begins executing, it checks for initialization files of the form .wind/filename.tcl in two places: first under usr/wind (that is, in the directory specified by the WIND_BASE environment variable), and then in the directory specified by the HOME environment variable (if that environment variable is defined). If any files are found, their contents are sourced as Tcl code when Tornado starts.
The Tornado.tcl file allows you to customize the Tools menu and tool bar, as well as other elements of the Tornado window. For example, you can have your own dialog box appear based on a menu item you add to any menu. For more information about the Tcl customization facilities available, see the Tornado API Guide or the Tornado Online Manuals: Tornado API.