newbie gtk install question

I'm sure I followed the instructions but although I can run a gtk application from a dos prompt I cannot get it to run from a browser. I get the following message (I've edited the paths in the message to shorten them): Warning: dl(): Not supported in multithreaded Web servers - use extension statements in your php.ini in c:\ ... \htdocs\gtktest\mh2.php on line 13 Fatal error: Cannot instantiate non-existent class: gtkwindow in c:\ ... \htdocs\gtktest\mh2.php on line 79 If I have an existing, working PHP installation at D:\PHP - am I right in thinking I have to install the gtk files OVER the existing php files. I'm using PHP 4.3.8 which has a php.exe size of 44kb. The gtk version is only 24kb. If I am supposed to install gtk in a different directory so that I have two PHP installations - how do I tell Apache which installation to use? Regards Mark Hutchinson AFX Ltd