The desktop client can only be closed using the "Quit" option from the tray icon menu. Closing the main window just minimizes the app to the background, leaving the process running.

On some desktop environments (looking at you, GNOME Shell), the tray menu isn't available. As a result, there’s no way to properly close the desktop app or clean up the tunnels.

Proposed solution: A "close" button and / or ctrl-q keyboard shortcut.