Better tolerance to network interuptions & Offline use for download client

Restore database connection and keep models open in case of connection interuption or -change:
This would remove the hassle to memorize and re-open all open models when the network connection is interupted (connect to docking station, move between meeting rooms, switch between direct internet and VPN, switch Wifi, ...)

Probable the above would alow allow at least view open models offline, e.g. to work during traveling.