fixed:send width of action column to View/Elements/table/grid_headers.ctp.

you can use width option to set width when addAction.
for example: 
$this->Grid->addAction(__('Active'), array( 'controller' => 'users' , 'action' => 'activeclient' ), array("/User/id"),array('width' => '30%' ));   
attention: all addAction method that used in your grid should have same width!