Gibberish term 'modal' in project deletion dialog

Summary

https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/views/shared/_confirm_modal.html.haml#L18 says 'close this modal to continue'. Almost nobody knows what a 'modal' is.

Possible fixes

What about "close this dialog"? Or "close this box"? Or "click the X at the top-right of this box"? Or "click 'close'"?