I am having the same problem with a site where users are entering critical data into a page using CKEditor.
They click on a Save button on the page to save the data, the same function being executed when the page is unloaded or the window is closed.
I am using "body onunload" which works fine in IE8, but doesn't work at all in Firefox or Chrome.
None of the other solutions I have found seem to work for Firefox or Chrome and then don't work for IE8 either.
The users are getting grouchy because they just moved from IE8 to Chrome for entering this data, and Chrome has a habit of updating itself and updating the page, which causes the report content to be lost.
Ideally I want to find an Unload trigger that works in IE8, Chrome and Firefox, but an alternative would be if I could save the data that they were typing every minute, a solution that I see mentioned here. Not sure how to go about that though. Could someone please point me in the right direction.