It would be very if you could add dependencies directly from the edit view of a task and/or milestone. It should include the four types of dependencies:
1. Finish to Start: Predecessor must finish before Successor can start.
2. Predecessor must start before Successor can start.
3. Predecessor must finish before the Successor can finish.
4. Predecessor must start before Successor can finish.

Graphical Representation: https://projectinsight.com/project-management-basics/task-dependencies

This also directly relates to my Gantt chart feedback (here: https://freedcamp.uservoice.com/forums/126945-suggestions-for-features/suggestions/41100613-update-the-gantt-chart-to-account-for-the-four-dep)