Hi Matej,
quick reply - i just found this:
css-tricks.com/snippets/htaccess/force-f...not-open-in-browser/
So, if you're on Apache and you have access to the .htaccess file on your server, adding the line:
AddType application/octet-stream .gpx
to that file could solve your problem. Please try it, and let us know if it works!
(i'm a bit short on time atm., will try it out myself asap.)
EDIT: i'm a bit stumped that Android and iOS can't even handle simple ZIP files,
it never got to me this
could even be a problem...
cheers, Frank