User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:2.0) Gecko/20100101 Firefox/4.0 Build Identifier: Firefox 4.0 Browse to a page on a website contaning a from with a javascrip check Dont fill in al the requierd fields Click on submit (Ok, Send, Yes....) The Javascript is shown and tells the user that not all requierd fields are filled in. This is done in the new GUI of Firefox 4.0 Now close the message an click on a different menu link on the website Click on back (return to the form) Again click on submit (Ok, Send, Yes....) You will see that the Javascrip message is shown in the old style. Reproducible: Always Steps to Reproduce: Browse to a page on a website contaning a from with a javascrip check Dont fill in al the requierd fields Click on submit (Ok, Send, Yes....) The Javascript is shown and tells the user that not all requierd fields are filled in. This is done in the new GUI of Firefox 4.0 Now close the message an click on a different menu link on the website Click on back (return to the form) Again click on submit (Ok, Send, Yes....) You will see that the Javascrip message is shown in the old style. Actual Results: The old javascript messaging gui is shown Expected Results: The new javascript messaging gui of firefox 4.0 should be shown

Build: Mozilla/5.0 (Windows NT 6.1; rv:2.2a1pre) Gecko/20110406 Firefox/4.2a1pre I was unable to verify the issue. Can you please be more clear on the steps to reproduce? Do you have an example website? Can you provide a screenshot/ screen video of the issue? Remaining Unconfirmed.

Can you provide an example page either a link to one or attach a single page example to the bug.