Call to undefined function: fckeditor_iscompatiblebrowser()

I tried using the PHP4 library that is bundled with fck, but, I get the following error:

Call to undefined function: fckeditor_iscompatiblebrowser()

It appears the PHP library is calling the iscompatiblebrowser() function, but, it doesn't actually exist in the bundled library.

Is there a newer PHP 4 library that works?

Thanks.