I started using Ganttlab and found it very useful.
This merge request adds new chart to the milestone page.
The new (top) chart displays the gant in a milestone level (color blue).
The tasks chart is at the bottom of the page, and displayed the tasks (color green) filtered by the 'selected' milestone.
When clicking on the Milestone chart is opens the milestone page at the gitlab.com web page
I found it very helpful to view and manage my team tasks at "high level" therefore I use the milestone level.