This code snippet shows how to select visualization elements via a program.
This example show how the SelectionManager is used to select visualization elements via a program.
The program SelectionHandling evaluates the events from the buttons "Up", "Down", "Left",
"Right" and "Click" for the first visualization client.
The method SelectNextElement will change the current selection. If the button "Click" is pressed,
then a mouse-up event is fired for the selected element and is displayed as "LastClick".
The function SelectElementAt selects the element with the element-id entered in the field above.