My experience of VirtualBox on Linux is mostly excellent, but there are a few areas in which host data would be good to bring into guests, for the purposes of updating informational widgets. For example, I’d like to see CPU activity and CPU core temperature in a guest VM, so I don’t need to minimise the full-screen window to check the host’s taskbar. Also, occasionally I see the guest clock drifting quite substantially from the host, so it would be good to have a way to keep an eye on that.
I imagine this would work by setting up an HTTP server in the host on a spare port, listening just on the localhost address, and waiting for requests from guests with the necessary software installed. Updates might be configurable, from every few seconds to every few minutes.
I’d like to display this as a widget in guests in the taskbar, ideally to work in popular GNU/Linux distributions such as Ubuntu and Mint.