Bug 294462 [FieldAssist] ControlDecoration#showHoverText doesn't check if the widget is visible
If the HOVER-Text is set on decoration of a widget which is invisible the Hover-Shell is still poping up because it doesn't check if the control is invisible make the Hover appearing somewhere on the screen.
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ControlDecoration.java
System.out.println("LISTENER LEAK>>>CHECK TRACE ABOVE"); 
			} else if (listenerInstalls < 0) {
				System.out
						.println("REMOVED UNREGISTERED LISTENERS>>>CHECK TRACE ABOVE"); 
			} else {
				System.out.println("ALL INSTALLED LISTENERS WERE REMOVED."); 
			}
		}
	}
	/**
	 * Return the rectangle in which the decoration should be rendered, in
	 * coordinates relative to the specified control. If the specified control
	 * is null, return the rectangle in display coordinates.
	 * 
	 * @param targetControl
	 *            the control whose coordinates should be used
	 * @return the rectangle in which the decoration should be rendered
	 */
	protected Rectangle getDecorationRectangle(Control targetControl) {
		if (getImage() == null || control == null) {
			return new Rectangle(0, 0, 0, 0);
		}
		
		Rectangle imageBounds = getImage().getBounds();
		Rectangle controlBounds = control.getBounds();
		int x, y;
		
		if ((position & SWT.RIGHT) == SWT.RIGHT) {
			x = controlBounds.x + controlBounds.width + marginWidth;
		} else {