Submit buttons in Rails come with a useful option :disable_with which will disable the button when clicked and change its label to something like "Please wait...".

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An annoying side effect of that feature is that when you use the back button to return to the form, the submit button will be greyed out and disabled.

A solution is to re-enable the submit button before leaving the page. This works in Rails 3:

$(window).unload(function() {
  $.rails.enableFormElements($($.rails.formSubmitSelector));
});