UNIX
-----
Get a source archive ruby-fltk-x.x.x.tar.gz, extract files from the archive,
run extconf.rb using ruby and build as follows:

  $ tar -xvzf ruby-fltk-x.x.tar.gz
  $ cd ruby-fltk-x.x
  $ ruby extconf.rb  [some options are available, do extconf.rb --help]
  $ make
  $ make install     [maybe you need to become root]

Here is a process for building an extension for FLVW widgets:
  $ cd flvw
  $ ruby extconf.rb
  $ make
  $ make install

If you use ruby-1.6.7, you should apply intern.h.diff as follows:

  $ cd /usr/local/lib/1.6/i686-linux/
  $ patch -p0 < ~/src/ruby-fltk-x.x.x/intern.h.diff

Windows
--------
Get a binary distribution ruby-fltk-x.x.x.cygwin.zip or
ruby-fltk-x.x.mingw.zip and run 'install.rb' as follows:

  $ ruby install.rb

If you don't have opengl32.dll and glu32.dll, download them at [1]
and put those DLL into a system directory.
Also you need the following DLL if you use the cygwin version:
  /bin/cygjpeg6b.dll
  /bin/cygpng2.dll
These DLLs are part of cygwin packages.

Note:
Cygwin and Mingw binary distribution include OpenGL extension module[3].


References
-----------
[1] OpenGL download page:
    http://www.opengl.org/users/downloads/index.html
[2] Cygwin:
    http://www.cygwin.com/
[3] OpenGL Interface for Ruby
    http://www2.giganet.net/~yoshi/
