I have a desktop file with this contents:
[Desktop Entry]
Name=Mozilla Firefox - default
Type=Application
Comment=Web Application
Exec=/usr/lib/firefox/firefox
Icon=/home/noit/Desktop/ff-channel-base-iconsets/dev/dev512.png
I launch this desktop file with various arguments from terminal and from c function g_app_info_launch_uris docs seen here:
How can I make the arguments that passed to the desktop file be passed to the Exec?
