Ttk's progressbar widget.
D. McC 2008 Mar 26: Can anyone here provide a quick tip on how to change the foreground color of the progressbar from the blah blue-gray default to a color of the programmer's choice?
MG I'm not 100% sure if this is the right way, but it seems to work for me when using the "alt" theme.
ttk::style configure TProgressbar -background $color