Split parent with split child ,how to find '+'

split parent with split child ,how to find ‘+’?
gantt.config.open_tree_initially = true;
gantt.config.open_split_tasks = false;

i still not find how to show ‘+’ of open tree?

The task #3.3 should not be displayed on a separate line at all. It works that way because of a bug in Gantt. It will be fixed in the future, but I cannot give you any ETA.

For now, if the open_split_tasks config is not enabled, the parent task with the split rendering mode, shouldn’t be open.
Another way is to enable the open_split_tasks config: