Load this FLash video and hover over a button or right-click: http://www.apexvj.com/hd/player?s=69525510 You can see that the coordinates are offset vertically. This bug is due to us not taking into account element padding when converting mouse coordinates. It seems plugin event translation is done in the Chromium WebKit layer which bases the translation on the top-left of the element (which the padding comes after). If you remove the padding-top from this page, the coordinates are correct. Chrome bug: https://code.google.com/p/chromium/issues/detail?id=164021
I checked and Safari on Mac doesn't have this issue.
I believe cpu@ is mr. plugins (as much as we have at least)? I know our plugin implementation is different from other WebKit ports, but I don't know the details.