Hi,
 
there is a mis-alignment on IE8 and lower. Mailbox list bottom needs an adjustion of 2px. It is caused by splitters dot.
 
Add within mail.html in the style section:
#mailboxlist-container
{
  <roundcube:exp expression="browser:ie ? ('bottom: 18px;') : ''" />
}
 
Also there was a incorrect quote in the new listcontrols ...
 
Attached is a new mail.html ...
 
Regards,
Roland