In the VirtualBox Manager, Groups can be collapsed and expanded by clicking on the carat to the left in the Group Header.
But you can also Enter and Leave groups too, either by using the right-arrow/left-arrow keys, or by clicking on the carat on the right hand side of the Group Header, like this:
..leading to a view of just the Group contents. You can Leave or return to the parent in the same way.
Don't worry if you are imprecise with your clicking, you can use a double click on the entire right half of the Group Header to Enter a group, and the left half to Leave a group. Double-clicking on the left half when you're at the top will roll-up or collapse the group.
The real power of Groups is not simply in arranging them prettily in the Manager. Rather it is about performing collective operations on them, once you have grouped them appropriately.
For example, let's say that you are working on a project (Project X) where you have a solution stack of:
- Database VM,
- Middleware/App VM, and
- a couple of client VMs which you use to test your app.
With VM Groups you can start the whole stack with one operation. Select the Group Header, and choose Start:
The full list of operations that may be performed on Groups are:
- Starts from any state (boot or resume)
- Start VMs in headless mode (hold Shift while starting)
- Save state
- Send Shutdown signal
- Discard saved state
- Show in filesystem
Hopefully we've shown that the introduction of VM Groups not only makes Oracle VM VirtualBox pretty, but pretty powerful too.