Device ID completion for locally discovered devices

[acolomb]

One feature I'm really missing in Syncthing-GTK is the auto-completion of locally discovered Device IDs when adding a new remote device.

In the Web UI, a completion list is displayed with local devices matching the characters typed so far. Clicking one of those and comparing the string is way more efficient than typing it all. Currently I always open the Web UI to add new (local) devices, because ST-GTK lacks the feature.

Could this be implemented please?