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
* 
	 * @return the Control that should be layed out in the field's parent's
	 *         layout. This is typically not the control itself, since
	 *         additional controls are used to represent the decorations.
	 */
	public Control getLayoutControl() {
		return form;
	}
	/**
	 * Create the parent composite and a form layout that will be used to manage
	 * decorations.
	 */
	private Composite createForm(Composite parent) {
		Composite composite = new Composite(parent, SWT.NO_FOCUS);
		
		
		composite.setLayout(new FormLayout());
		return composite;
	}
	/**
	 * Add any listeners needed on the target control.
	 */
	private void addControlListeners() {
		control.addDisposeListener(new DisposeListener() {
			public void widgetDisposed(DisposeEvent event) {
				if (hover != null)
					hover.dispose();
			}
		});
		control.addFocusListener(new FocusListener() {