In case if we have form with password field on it and form validation performed by JS function attached to onSubmit event (<form onsubmit="return validateForm()">) FireFox displays "Remember Password" dialog when you try to submit the form regardless of validation result. So even if function validateForm returns false and form will not be actually submitted, remember password dialog will appear. The same thing with buttons on such form. For example: we have button to run some JS script on the form <button onclick="soSomething(); return false"> When button clicked, "Remember Password" dialog will appear, but form actually is not submitted.