symfony - Symfony2, Sonata : Collapsed group -

I'm trying to do something relatively simple but it does not work.

I want to increase the user experience to be able to collapse the groups in Sonata.

  - & gt; (With 'MyGroups', the array ('collapsed' = & gt; true)) -Ed ('myfield') - & gt; the ending ();  

It is based on Sonata.

Very simple, but I can not see why it does not work. Is the array ('collapsed' => true) not enough?

Is this a problem?

The short option has been removed in the latest version of Sonata:

< Li>

Available in 2.1

• 2.2 And in the latest it is not, there is only one reference to the file collapse, which is for the CSS class.

Changelog 2.2: