Adds a button to the ipython notebook toolbar to hide/show the input code cell. To use it, you have to put the custom.js file in your `.ipython_<profile name>/static/custom/` folder, where *<profile name>* is the ipython profile in use.

custom.js

$([IPython.events]).on('notebook_loaded.Notebook', function(){
    IPython.toolbar.add_buttons_group([
        {
             'label'   : 'toggle input cells',
             'icon'    : 'icon-refresh', 
             'callback': function(){$('.input').slideToggle()}
        }
    ]);
});

See Carreau's blog post's on how to customize the ipython notebook css and js.

Sorry I had to remove part of your comment on custom.js issue.
We can discuss about why privately by mail if you want.