Piwik click tracking should use the click event instead of the mousedown event because:
1.) mousedown is not the same as a click and it should be tracking clicks.
2.) The current way of doing things prevents the right-click menu from appearing until the tracking code has run, which can take a long time for downloads or external links.
Yes, this is inconsistent from the GA, MS, and Y! tracking code.
While this is already moot in the new piwik.js under development -- the delay is deferred to the unload -- I will change this to be consistent with other trackers.
See #5287 track file download and outlinks when user opens URL with Right click (opens new tab)