This enum specifies how events are generated when the mouse gets dragged over a particular interactor.
Default behavior: drag "over" an interactor. In this case, all MouseMove events will be directed to the interactor in which the mouse button was originally pressed, even if the mouse moves "outside" the interactor or "over" one of its children. This also holds for the final MouseUp event. This behavior is useful in many cases, including selection of text or resizing.
Drag-and-Drop behavior. Indicates that the interactor can be dragged. In this case, only two events will be directed to the dragged interactor: OnPaint and OnDragPaint. The OnDragPaint event will be fired last and offers a Graphics coordinate system that reflects the position of the dragged interactor. This allows the dragged interactor to draw a custom representation while dragging. If the interactor gets dragged over another interactor, a number of "Drag" events will be directed to this other interactor: DragEnter: The dragged interactor "enters" the interactor.DragMove: the dragged interactor moves over the interactor.DragDrop: the dragged interactor gets dropped on the interactor.DragLeave: the dragged interactor "leaves" the interactor or dragging failed.
In this case, the viewer will draw a drag rectangle during dragging and it will generate "DragSelect" events for the interactor that specifies this behavior, as wel as all its children. This behavior is useful for selecting interactors, or for marking an area relative to the viewer.