How to have php cli and php-gtk installed without problems

All,

I have a problem.

I've added these lines to the /etc/php5/cli/php.ini  file

; added for and by php5-gtk rpm package
; add more extension lines after this one if you have more .so files that
should
; be loaded.
extension=php_gtk2.so

But this has as side effect that php scripts that are run from the cron
like the cacti poller.php don't work. As they cant open the display.

Now i wonder how I can solve this issue.
That for example Phoronix Test Suite use the php-gtk extension.
But poller.php don't use the php-gtk extension.

Regards,

Joop.