[RCU] Dependency of Roundcube 0.5.1 to php > 5.2.1

Hi,

I have installed the current bugfix-release on a server running php 5.2.0 and it seemed to work fine. I have no possibility to upgrade the php version on the machine.

Which parts of roundcube 0.5.1 depend on the newer php version? What functionality should I expect to stop working? Would it be possible to bypass this by a small patch or is the dependency weaved into central parts of roundcube?

I would be glad to get this information to decide whether I can use newer roundcube versions or have to stay with the old ones or switch to another webmail frontend.

Greetings,

Fred