Here is a short video demonstrating how to add a dependency between tasks:
as part of smtk!2955.
Any operation that creates arcs can be registered to the smtk::operation::ArcCreator group and will appear in the combo-box for users to select. Any qtBaseTaskNode object in the scene can be chosen as an endpoint; if the currently-selection arc-creation operation does not allow that node to serve as the source or destination endpoint, the node will be highlighted in red. If the operation does not allow the combination of endpoints (i.e., its ableToOperate() method returns false), then the arc between the selected nodes will be drawn in red. Once the user has properly configured both endpoints (by clicking on each endpoint in order such that the arc preview is drawn in green), the operation is launched.
The same merge request adds the mode buttons and task selection to the task panel. You can now bulk-select tasks and move them together.