Bug 335308 [JFace] JavaDoc of ControlDecoration#setDescriptionText is wrong
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ControlDecoration.java
printRemoveListener(target, "MOUSEMOVE"); 
					target.removeMouseMoveListener(mouseMoveListener);
					moveListeningTarget = null;
				}
				hideHover();
			}
			public void mouseHover(MouseEvent event) {
				if (showHover) {
					decorationRectangle = getDecorationRectangle((Control) event.widget);
					if (decorationRectangle.contains(event.x, event.y)) {
						showHoverText(getDescriptionText());
						Control target = (Control) event.widget;
						if (moveListeningTarget == null) {
							printAddListener(target, "MOUSEMOVE"); 
							target.addMouseMoveListener(mouseMoveListener);
							moveListeningTarget = target;
						} else if (target != moveListeningTarget) {
							printRemoveListener(moveListeningTarget,
									"MOUSEMOVE"); 
							moveListeningTarget
									.removeMouseMoveListener(mouseMoveListener);
							printAddListener(target, "MOUSEMOVE"); 
							target.addMouseMoveListener(mouseMoveListener);
							moveListeningTarget = target;
						} else {
							
						}
					}
				}
			}