$ ruby mikutter.rb 
./userconfig.rb:8:in `require': no such file to load -- gtk2 (LoadError)
        from ./userconfig.rb:8
        from /$DIR/core/utils.rb:47:in `require'
        from /$DIR/core/utils.rb:47:in `miquire'
        from ./mui/gtk_extension.rb:2
        from /$DIR/core/utils.rb:50:in `require'
        from /$DIR/core/utils.rb:50:in `miquire'
        from /$DIR/core/utils.rb:49:in `each'
        from /$DIR/core/utils.rb:49:in `miquire'
        from ./plugin/gui.rb:7
        from /$DIR/core/utils.rb:50:in `require'
        from /$DIR/core/utils.rb:50:in `miquire'
        from /$DIR/core/utils.rb:49:in `each'
        from /$DIR/core/utils.rb:49:in `miquire'
        from ./plugin/plugin.rb:335
        from /$DIR/core/utils.rb:47:in `require'
        from /$DIR/core/utils.rb:47:in `miquire'
        from ./watch.rb:3
        from /$DIR/core/utils.rb:47:in `require'
        from /$DIR/core/utils.rb:47:in `miquire'
        from $DIR/mikutter.rb:19