Problem with PHP 5.2.5 and ini_set to change include_path (vital function!)

[fabian]

Hi folks.
I've got a problem since my provider upgraded to the latest PHP version of 5.2.5:
Roundcube (which worked fine for months and which I allways enjoyed much using) declines to function.
I've tracked it down to the following:
In PHP 5.2.5 there's been a bugfix which changed the behavior of the "ini_set" command vital to roundcube mainfunctions. Its no longer that easy to override the systemwide-standard-include-paths for locating scripts. Since many scripts in roundcube are not called relativly to the rootdirectory it stops functioning.
I'm aware of similar postings earlier in this forum and also of the help provided on php.net which suggests putting some "php_value" instructions in the root .htaccess file instead of using the ini_set function.
BUT: in (maybe not only) my case (with my webspace-provider) there seems to be a problem with changing the very restrictive "php_admin_value" in the main httpd.conf file of the apache server and therefore any attempt of changing the "include_path" value afterwards (in which way ever!) doesn't work - hence Roundcube doesn't work!
Is there any other chance of fixing this problem?
Or would I (or who ever) have to change all the relative path-calls within Roundcube to absolute ones so they wouldn't depend on the manually changed "include_path" anymore?
I assume that this would make necessary some changes very deep in the programm-core (if that is at all possible).

Any ideas?

Thanks a lot,
cheers,
Fabian