insertNode() is similar in is performance to insertRow(), but it should be used in a dialog controlling a tree view:
DIALOG.InsertNode("screen_array", index)
Here, index is an integer value that specifies the sibling node in the program array before which the current one is to be inserted.
There is some specifics about using variables with ui.Dialog methods.
You can learn about them here.
When insertNode() passes the index to the next sibling node. In program array, the parent-id member of the new node gets the parent-id of the next sibling node. After that the internal tree structure is automatically rebuilt.