When using Enter New, the Close button does not save edits, or warn of unsaved changes. I have tried Enter New in popup forms, in this scenario and have confirmed results. If something is supposed to work, I need to depend on it to work all of the time. As you know, popup forms allow you to do a modal operation, and additionally take advantage of a wider form, than displaying an entry form in a tab at the top.
Additionally, I have defined all Panel Operations at the top (Close Save, etc...), above the form (where they should always be defined IMO) , so I do not need or want to show any buttons at the bottom.
So, unfortunately, since the Enter New does not work for me, I do not use it.
Dave