you might want to get a little more familiar with how "require" actually works. You could use require and give the namespace you just loaded into the Clojure runtime an alias using ":as", alternatively you could refer to the functions of the required namespaces with their full name, i.e. "seesaw.core/native!".
In addition to that, you usually don't call (require...) directly but use the ":require" form in your namespace declaration. If you look at other Clojure code e.g. on github you will find this form most often.
Kind regards,
stefan