Perhaps the ideal approach here would be to pass TMP_DIR and OUT_DIR into the Tcl/Tk builds, so we can tell them where to put stuff.  However, that would require major surgery to Tix's makefile to get it to build.  I'd be +1 on doing so (since we're pretty much the de-facto maintainers of Tix at this point, as far as I can tell), but am not enthusiastic about actually doing it.  I'd be much more enthusiastic about deprecating Tix.

Steve, if the patch as given is good enough for you, I'm fine with applying it.