To compile 'tcltklib', you must have Tcl/Tk libraries on your environment. 
Although 'extconf.rb' script searches Tcl/Tk libraries and header files
(as default, searches tclConfig.sh/tkConfig.sh and use the defintions on
those; ActiveTcl has high priority on searching unless --without-ActiveTcl),
sometimes fails to find them. And then, 'tcltklib' cannot be compiled. If 
Tcl/Tk libraries or header files are installed but are not found, you can 
give the information by arguments of the 'configure' script. Please give 
some or all of the following options. 

 --with-tk-old-extconf         use old "extconf.rb" (default: false).
                               If current extconf.rb doesn't work properly
                               (or your install process is based on old 
                               documant about Ruby/Tk install), please try
			       this option.

 --with-ActiveTcl / --without-ActiveTcl
 --with-ActiveTcl=<dir>        search ActiveTcl libraries (default: true).
                               When true, try to find installed ActiveTcl. 
                               When <dir> is given, use it as the ActiveTcl's
			       top directory (use <dir>/lib, and so on).
                               Old "extconf.rb" doesn't support this option.

 --with-tk-shlib-search-path=<paths>
                               teach the paths for loading shared-libraries 
                               to linker.
                               <paths> is a path list with the same format 
                               as PATH environment variable.
                               This option may be experimental.
                               Old "extconf.rb" doesn't support this option.

 --with-tcltkversion=<version> 
      force version of Tcl/Tk libaray
      (e.g. libtcl8.4g.so ==> --with-tcltkversion=8.4g)

 --without-tcl-config / --without-tk-config
 --with-tclConfig-dir=<dir>       
 --with-tkConfig-dir=<dir>     the directory contains 'tclConfig.sh' and 
                               'tkConfig.sh'. 
			       Current "extconf.rb" uses the information 
                               on tclConfig.sh/tkConfig.rb, if possible.
                               Old "extconf.rb" doesn't support this option.

 --with-tcllib=<libname>       (e.g. libtcl8.4.so ==> --with-tcllib=tcl8.4)
 --with-tklib=<libname>        (e.g. libtk8.4.so  ==> --with-tklib=tk8.4)

 --enable-tcltk-stubs          (if you force to enable stubs)
                               On old "extconf.rb", default is false.
                               On current "extconf.rb", default is true when 
                               tclConfig.sh/tkConfig.sh have TCL_STUB_LIB_SPEC
                               /TK_STUB_LIB_SPEC, else default is false.

 --with-tcl-dir=<path> 
      equal to "--with-tcl-include=<path>/include --with-tcl-lib=<path>/lib"

 --with-tk-dir=<path> 
      equal to "--with-tk-include=<path>/include --with-tk-lib=<path>/lib"

 --with-tcl-include=<dir>      the directry contains 'tcl.h'
 --with-tk-include=<dir>       the directry contains 'tk.h'

 --with-tcl-lib=<dir>          the directry contains 'libtcl<version>.so'
 --with-tk-lib=<dir>           the directry contains 'libtk<version>.so'

 --enable-mac-tcltk-framework  (MacOS X) use Tcl/Tk framework
                               (Obsolete. Please use '--enable-tcltk-framework'.)

 --enable-tcltk-framework      use Tcl/Tk framework

 --with-tcltk-framework=<dir>  the directory contains Tcl/Tk framework; 
                               "<dir>/Tcl.framework" and "<dir>/Tk.framework".
                               When this option is given, it is assumed that 
                               --enable-tcltk-framework option is given also.

 --with-tcl-framework-dir=<dir>
      Tcl framework directory (e.g. "/Library/Frameworks/Tcl.framework")

 --with-tk-framework-dir=<dir>
      Tk framework directory (e.g. "/Library/Frameworks/Tk.framework")

 --with-tcl-framework-header=<dir>
      Tcl framework headers directory 
      (e.g. "/Library/Frameworks/Tcl.framework/Headers")

 --with-tk-framework-header=<dir>
      Tk framework headers directory 
      (e.g. "/Library/Frameworks/Tk.framework/Headers")


 --with-X11 / --without-X11    use / not use the X Window System

 --with-X11-dir=<path> 
      equal to "--with-X11-include=<path>/include --with-X11-lib=<path>/lib"

 --with-X11-include=<dir>      the directry contais X11 header files
 --with-X11-lib=<dir>          the directry contais X11 libraries


If you forgot to give the options when do 'configure' on toplevel
directry of Ruby sources, please try something like as the followings.

 $ cd ext/tcltklib
 $ rm Makefile
 $ CONFIGURE_ARGS='--with-tcl-include=/usr/local/include/tcl8.4/ --with-tcllib=tcl8.4 --with-tklib=tk8.4' ruby extconf.rb


 *** ATTENTION ***
When your Tcl/Tk libraries are compiled with "pthread support", 
Ruby/Tk may cause "Hang-up" or "Segmentation Fault" frequently. 
If you have such a trouble, please try to use the '--enable-pthread' 
option of the 'configure' command and re-compile Ruby sources. 
It may help you to avoid this trouble. The following configure 
options may be useful.

  --enable-tcl-thread/--disable-tcl-thread
  --with-tclConfig-file=<path of 'tclConfig.sh'>
  --with-tkConfig-file=<path of 'tkConfig.sh'>

It is not need that 'tclConfig.sh' is a normal Tcl/Tk's tclConfig.sh. 
But the file is expected to include the line "TCL_THREADS=0" or "...=1".
When no "TCL_THREADS=?" line, if Tcl version is 7.x or 8.0 which is 
given by "TCL_MAJOR_VERSION=?" line and "TCL_MINOR_VERSION=?" line, 
then --disable-tcl-thread is expected. Else, ignore the 'tclConfig.sh'.
If --enable-tcl-thread or --disable-tcl-thread option is given, then 
--with-tclConfig-file option is ignored. 

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