I have a form with an action on submit, which does last a bit longer (can be up to two minutes of computing). When the Form is submitted, the action has to send some emails, upload files and do some other kind of stuff. Is it possible to start an overlay (greybox or something) with a loading indicator image inside it, when the submit button is clicked and before the submit is computed? Or is there any other way, to not make the user believe that the application was hung up? what about sending forms by ajax? how to handle the response?
As a speciality, my frontend form includes some uploaded files with the MultipleFileUploadField (Uploadify module by uncle cheese).