Plugin for filtering based on query string parameters

In a recent project I used menu position to define the position based on a specific content type. However, it happened that we needed two different positions for the same content type, based on the page that is linking to it. Our solution was to add a parameter on the query string with the name of the referral. So assuming that A and B are pages both linking to the content type page C, the final query string would be C?A or C?B.

We developed a small plugin for menu position that basically adds this filtering capabilities: you specify a list of query string keys (separated by new lines) that should be present in the URL in addition to other menu position rules. This could be extended in the future to evaluate the full query string args (including not only the key, but also the value).