Grouping activities can be a convenient way to organize your project as it increases in complexity.
Each group is like a WBS level (Work Breakdown Structure). Each Group can be expanded to get a fully functional Canvas.
How to create a Group
To convert a single Activity into a group, right-click on the activity. The context menu of will show Conver to Group
To convert multiple activities to a group:
Select multiple activities by pressing <Ctrl> key and while keeping it pressed, draw a box around the activities
Then, click on Convert to Group in the context menu
How to ungroup an existing group
To ungroup, right-click on the group and click on Ungroup from the context menu