I found a solution that works fine for me:
In terminal type:
defaults write com.apple.LaunchServices LSHandlers -array-add \ "<dict><key>LSHandlerContentTag</key> <string>gpx</string><key>LSHandlerContentTagClass</key> <string>public.filename-extension</string><key>LSHandlerRoleAll</key> <string> com.apple.dt.document.gpx </string></dict>"
then
/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -domain local -domain system -domain user
Topic:
Developer Tools & Services
SubTopic:
Xcode
Tags: