screenshare Weston plugin uses private libweston API
Screenshare plugin needs to deliver input events into the core compositor, but libweston does not offer any public API to do that. Therefore screenshare violates the API rules and uses the backend API to deliver input.
Either screenshare needs to become a libweston plugin instead of being a Weston plugin (short term specific solution), or libweston needs to grow a public API for delivering input events (long term generic solution).