Bug 129214 [Field Assist] - Decorated Field attachments not centering images horizontally
DecoratedField is supposed to center decorations horizontally on each side. The current attachments are not doing so. Also consider whether grid would have been a better choice for internal implementation.
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/DecoratedField.java
formData = null;
			break;
		case RIGHT_BOTTOM:
			if (decDatas[RIGHT_TOP] == null
					|| decDatas[RIGHT_TOP].data.width < newWidth) {
				formData.right = new FormAttachment(decData.label);
			} else
				formData = null;
			break;
		default:
			return;
		}
		if (formData != null) {
			
			control.setLayoutData(formData);
			form.layout();
		}
	}
	/**
	 * Get the control that is decorated by the receiver.
	 * 
	 * @return the Control decorated by the receiver, or <code>null</code> if
	 *         none has been created yet.
	 */
	public Control getControl() {
		return control;
	}
	/**
	 * Get the control that represents the decorated field. This composite
	 * should be used to lay out the field within its parent.