Isnt it better to add a a "genwall.sudoers" in "/etc/sudoers.d/" ?
and then you can remove the sudo from the desktop file i really dont know the different but this is what all devs doing
To use the icon from application browser you need to have sudser installed.
user ALL = NOPASSWD: /usr/sbin/genwall
user ALL = NOPASSWD: /opt/genwall/bin/genwall