Show dropdown button for Opportunities subpanel in Account

Hi,

In Sugar 7, if we enter to the record view of an account, in the opportunities subpanel, it is disabled the dropdown button to choose existing opportunities.

How I could enable it? (I have seen ./modules/Accounts/clients/base/layouts/subpanels/subpanels.php, but there isn't any 'override_paneltop_view' property) 

Thank you very much.

Kind Regards,
Rubén Recacha
Consultant REDK Software Engineering