ActiveTcl is ActiveState's quality-assured distribution of Tcl. 

# see <http://www.activestate.com/Products/ActiveTcl/>
#     <http://www.tcl.tk/>

First of all, please try to configure without any options.
"extconf.rb" searches ActiveTcl as default action.
If you have ActiveTcl and standard (or your own) Tcl/Tk on your
environment and don't want to use ActiveTcl on your Ruby/Tk, please
use --without-ActiveTcl option.

When "extconf.rb" fails to find your ActiveTcl libraries, please try
the followings.

If you want to use ActiveTcl binary package as the Tcl/Tk libraries, 
please use the following configure options.

   --with-ActiveTcl=<ActiveTcl_root>
     ( When without argument; no <ActiveTcl_root>; only '--with-ActiveTcl', 
       it same to '--with-ActiveTcl=/opt/ActiveTcl*/lib' )

   --with-tcl-dir=<ActiveTcl_root>
   --with-tk-dir=<ActiveTcl_root>

And use the followings if you need.

   --with-tcllib=<libname>
   --with-tklib=<libname>
   --enable-tcltk-stubs

For example, when you install ActiveTcl-8.4.x to '/usr/local/ActiveTcl', 

   configure --with-tcl-dir=/usr/local/ActiveTcl/  \
             --with-tk-dir=/usr/local/ActiveTcl/   \
             --with-tcllib=tclstub8.4              \
             --with-tklib=tkstub8.4                \
             --enable-tcltk-stubs

It depends on your environment that you have to add the directory of 
ActiveTcl's libraries to your library path when execute Ruby/Tk. 
One of the way is to add entries to TCLLIBPATH environment variable, 
and one of the others add to LD_LIBRARY_PATH environment variable

Probably, using TCLLIBPATH is better. The value is appended at the 
head of Tcl's 'auto_path' variable. You can see the value of the 
variable by using 'Tk::AUTO_PATH.value' or 'Tk::AUTO_PATH.list'.

For example, on Linux, one of the ways is to use LD_LIBRARY_PATH 
environment variable. 
-------------------------------------------------------------------------
 [bash]$ LD_LIBRARY_PATH=/usr/local/ActiveTcl/lib:$LD_LIBRARY_PATH \
         ruby your-Ruby/Tk-script

 [bash]$ LD_LIBRARY_PATH=/usr/local/ActiveTcl/lib:$LD_LIBRARY_PATH irb
-------------------------------------------------------------------------
Based on it, the Tcl interpreter changes auto_path variable's value.

Then, you'll be able to use Tcl/Tk extension libraries included in the
ActiveTcl package (e.g. call TkPackage.require('BWidget'), and then,
use functions/widgets of BWidget extention). 

                                  Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp)