Currently there is no possibilities to say Piwik that a site search performs as expected.
For example if I have an internal search engine and that someone typed a search in it.
If the guy do not click on the search results but on another link within the site such as the contact page. From Piwik point of view this internal search is considered as a success whereas it is not really one.
It would be great if there was some kind of code we could add in order to say, if a click occurs on those links only then it is a success, if not then it is a search exit.