Modifying the tree during dialog execution
The tree-view content can be changed while executing the DISPLAY ARRAY
dialog. 
During the DISPLAY ARRAY execution, it is possible to modify the content of the
                        tree model (that is the program array), by inserting, adding or removing
                        nodes by program. 
However, it is not recommended to directly modify the program array: you must use
the dialog class methods DIALOG.insertNode(), DIALOG.appendNode(), and DIALOG.deleteNode() to modify the tree model instead. By using these methods, the
dialog can synchronize internal data, otherwise the tree display would be corrupted.
It is recommended to be in UNBUFFERED mode to
get a front-end synchronization       of the tree-view content.