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 position
	 *            The SWT constant indicating the position of the decoration
	 *            relative to the field's control. The position should include
	 *            style bits describing both the vertical and horizontal
	 *            orientation. <code>SWT.LEFT</code> and
	 *            <code>SWT.RIGHT</code> describe the horizontal placement of
	 *            the decoration relative to the field, and the constants
	 *            <code>SWT.TOP</code> and <code>SWT.BOTTOM</code> describe
	 *            the vertical alignment of the decoration relative to the
	 *            field. Decorations always appear on either horizontal side of
	 *            the field, never above or below it. For example, a decoration
	 *            appearing on the left side of the field, at the top, is
	 *            specified as SWT.LEFT | SWT.TOP. If an image decoration
	 *            already exists in the specified position, it will be replaced
	 *            by the one specified.
	 * @param showOnFocus
	 *            <code>true</code> if the decoration should only be shown
	 *            when the associated control has focus, <code>false</code> if
	 *            it should always be shown.
	 * 
	 */
	public void addFieldDecoration(FieldDecoration decoration, int position,
			boolean showOnFocus) {
		final Label label;
		FormData formData;
		int i = indexForPosition(position);
		if (decDatas[i] == null) {
			formData = createFormDataForIndex(i, decoration.getImage());
			label = new Label(form, SWT.HORIZONTAL | SWT.VERTICAL | SWT.CENTER);