看起来Firebug（Firefox附加组件）具有答案：
- open Firebug
- right click the element in HTML tab
- click Log Events
- enable Console tab
- click Persist in Console tab (otherwise Console tab will clear after the page is reloaded)
- select Closed (manually)
- there will be something like this in Console tab:
...mousemove clientX=1097, clientY=292popupshowingmousedown clientX=1097, clientY=292focusmouseup clientX=1097, clientY=292click clientX=1097, clientY=292mousemove clientX=1096, clientY=293...
