Chapter 49. Tcl 7.5/Tk 4.1
Tk 4.1 is notable for its cross-platform support. Your Tk scripts can run on Windows, Macintosh, as well as UNIX. The associated Tcl release, 7.5, saw significant changes in event-driven I/O, network sockets, and multiple interpreters.
Cross-platform support, network sockets, multiple Tcl interpreters, and an enhanced foreach command are the highlights of Tcl 7.5 and Tk 4.1.