The Desktop automatically discovers applications that have a .desktopfile in the /usr/share/applicationsdirectory. This file always starts with "[Desktop Entry]" and continues with a number of key value pairs that define the application to the Desktop, including:
the file name of the application's executable -- the
Execkey
the name of the the application to display in the
applications menu -- the
Namekey
the file name (without the file extension) of the icon to
display along with the name in the applications menu, if any -- the
Iconkey
Here's a sample .desktop file:
[Desktop Entry] Version=1.0.0 Encoding=UTF-8 Name=PyGlade Type=Application Exec=/usr/bin/pyglade Terminal=false Icon=pyglade_26 Categories=Applications
Currently, applications with a valid .desktop file are presented to the user in the (Applications) > Extras menu.
The executable and icon files are described below.