Extended Metadata on Right Click on Layer

Details are in Available Plugins documentation:

Informations about groups / layers
Display informations for each group or layer from the mapfile. For instance, if you use grpInfoLink with value 1 or 2 in your
configuration file, when clicking on a group name or on the associated icon, a dynamic window will appear and display the
long description about this group.
Activation
To activate this plugin, simply add "infos" in your plugin list. If you don't specify the infosMetadata in your configuration file,
the MATADATA fiel named DESCRIPTION will be used.
Customize your informations
Simply specify infosMetadata = "MY_LONG_DESCRIPTION" to use the METADATA field named
MY_LONG_DESCRIPTION for instance.