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
* 
	 * @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
	 *            control that is to be decorated.
	 * 
	 * @see IControlCreator
	 */
	public DecoratedField(Composite parent, int style,
			IControlCreator controlCreator) {
		this.form = createForm(parent);
		this.control = controlCreator.createControl(form, style);
		addControlListeners();
		form.setTabList(new Control[] { control });
		
		FormData data = new FormData();
		data.left = new FormAttachment(0, 0);
		data.top = new FormAttachment(0, 0);
		data.right = new FormAttachment(100, 0);
		control.setLayoutData(data);
	}
	/**
	 * Adds an image decoration to the field.
	 * 
	 * @param decoration
	 *            A FieldDecoration describing the image and description for the
	 *            decoration