The listener interface for receiving display change events. The class that is interested in processing a display change event implements this interface (and all the methods it contains). For Motif, this interface is only used for dragging windows between Xinerama screens. For win32, the listener object created from that class is then registered with the WToolkit object using its addDisplayChangeListener method. When the display resolution is changed (which occurs, in Windows, either by the user changing the properties of the display through the control panel or other utility or by some other application which has gotten fullscreen-exclusive control of the display), the listener is notified through its displayChanged() or paletteChanged() methods.