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
* <code>setUseMaximumDecorationWidth(false)</code> and need not register
 * their decorations.
 * <p>
 * This class is not intended to be subclassed.
 * 
 * @since 3.2
 * 
 * @see FieldDecorationRegistry
 */
public class DecoratedField {
	/**
	 * Cached platform flags for dealing with platform-specific issues.
	 */
	private static boolean CARBON = "carbon".equals(SWT.getPlatform()); 
	/**
	 * Constants describing the array indices used to hold the decorations in
	 * array slots.
	 */
	private static final int LEFT_TOP = 0;
	private static final int LEFT_BOTTOM = 1;
	private static final int RIGHT_TOP = 2;
	private static final int RIGHT_BOTTOM = 3;
	private static final int DECORATION_SLOTS = 4;
	/**
	 * Simple data structure class for specifying the internals for a field
	 * decoration. This class contains data specific to the implementation of
	 * field decorations as labels attached to the field. Clients should use
	 * <code>FieldDecoration</code> for specifying a decoration.
	 */
	private class FieldDecorationData {