Can't resolve target of expression 'Zend/Pdf/Exception.php'

I am using some Zend libs. In order to use them I add the path to the libs to the include_path:
set_include_path(get_include_path() . PATH_SEPARATOR . KERNEL_DIR . 'common/libs/');
require_once(KERNEL_DIR . 'common/libs/Zend/Pdf.php');

One of Zend classes includes an Exception.php file:
require_once 'Zend/Pdf/Exception.php';

But when I ctrl+click on it, it says:
Can't resolve target of expression 'Zend/Pdf/Exception.php'

So my suggestion is to make the IDE search for included files taking into account all include paths returned by get_include_path().