Don't submit post until attachment upload completes

Hi,

I have noticed that when adding a new post, users can click the Submit button while their attachment is still uploading, and then it is not attached to the post. Some large files take around 30 seconds to upload on my site, and I don’t want the user to be able to submit the post while it is still in the process of uploading.

How can I implement some form of validation where the user can’t click Submit until their upload is complete, if they choose to upload an attachment?

Thank you!

http://ww.wp.xz.cn/extend/plugins/wp-user-frontend/