Apr 5 2017
I don't see veaction=edit on the documentation.
But I see useve=true was deleted some month ago from the page : https://www.mediawiki.org/w/index.php?title=Extension:InputBox&diff=2336352&oldid=2331664
Apr 4 2017
To complete : and when i had "useve=true" , the button open a page "this page does not exist yet"