I created a client with "force SuExec" options turned on.
When client creates a site, everything is OK, but when he creates a vhost subdomain, "force suexec" rule is not applicated and subdomain has suexec disabled.
I solved this by changing line 387 in /interface/web/sites/web_vhost_subdomain_edit.php
if($client['force_suexec'] != 'n') $this->dataRecord['suexec'] = '-';
if($client['force_suexec'] != 'n') $this->dataRecord['suexec'] = 'y';
don't know, if it is a correct solution, but it works
I have no account at bugtracker, so I write it here