I'm trying to run this program SLab, and I get this error message when
running the program:

libtk8.0.so: cannot open shared object file

I have tcl/tk installed, and I've found a file called libtk.so and one
called libtk8.3.so in the /usr/lib/ folder.  So it seems to me like my
versions are too new.  but that doesn't make any sense.  Shouldn't
this stuff be backwards compatible?  They're run-time libraries.  I
just don't understand what's going on here.

thanks
jake