Vidalia is a type of onion and was a GUI software program for controlling and viewing the inner workings of the Tor onion router anonymity-network. It was built using version 4 of the Qt toolkit.
Vidalia development was discontinued a decade (or more, depending on when you read this) ago.
It was a nice Interface for controlling Tor and viewing a map of the network
Vidalia displayed a list of running Tor server on the left side of the screen and you could click on any of these servers to get all sorts of less interesting information like their bandwidth, uptime, operating system, IP and Tor-version.
The map, when monitoring a server node, would become messier the longer it ran:
Vidalia also had a Tor bandwidth monitor:
There has not been any Vidalia development for 10+ years. It is possible to get the source-code from archive.org and it is probably possible to port it to Qt5 and modern Tor versions given enough time and effort.
Discontinued (outdated) Tor GUIs: