Plugin interface improvements would definitely be highly appreciated as well. Here is my wish list 
- Set the ground state flag (currently this value can only be read)
Use case: implementation of datalink clearance where the flag is set automatically when confirmation is received - Allow to compose messages in the entry field of the command line, extending the ES default options for auto… messages
Use case: Add autotext messages for specific (plugin created) actions when the selected pilot is text only - Provide the status of a SCT file entry (active or not)
Use case: Toggle the display of specific entries (with functions, or commands) like MRVA, airspaces, terminal procedures etc. This is not possible today because the initial state of a SCT entry is not known. Therefore toggling is only possible for a specific item after a first explicit display/hide action by the plugin. And even then, the status is still not known to other plugins. - Provide all details/fields of the ESE file in existing/new functions
Use case: Customized SID/STAR lists indicating unavailable entries (due to meteo factors, airspace assignment, etc.), using the controllers radio call sign for CPDLC (composing a text message for the frequency transfer including the call sign from the ESE list) - Possibility to receive ES version information (both from the local instance and from other controllers)
Use case: plugin compatibility checks
The local instance version is required to adapt a plugin behaviour depending on the changes to the core functionalities. This would be a very handy method to ensure compatibility because you can always check the “minimum required ES version” for a plugin. Client information of other controllers can already be received via the .inf command. But it would be very helpful to access this information, too. Mainly to check what data can be exchanged/accepted by the other client. - Provide plugin list items
Use case: cooperation/interaction between plugins could be improved if data is available of the plugins loaded in the current instance. This could also allow a single plugin to make checks about the version/compatibility of all plugins.