Bug 126527 [Field Assist] - API - Field Decoration alignment issues are different for cell editors
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/DecoratedField.java
Point e = gc.textExtent(text);
			gc.dispose();
			e.x += hm * 2;
			e.y += hm * 2;
			return e;
		}
		/*
		 * Compute a new shape for the hover shell.
		 */
		void setNewShape() {
			Region oldRegion = region;
			region = new Region();
			region.add(getPolygon(false));
			hoverShell.setRegion(region);
			if (oldRegion != null) {
				oldRegion.dispose();
			}
		}
	}
	/**
	 * Construct a decorated field which is parented by the specified composite
	 * and has the given style bits. Use the controlCreator to create the
	 * specific kind of control that is decorated inside the field.
	 * 
	 * @param parent
	 *            the parent of the decorated field.
	 * @param style
	 *            the desired style bits for the field.
	 * @param controlCreator
	 *            the IControlCreator used to specify the specific kind of