Bug 140160 [Field Assist] - JAVADOC ONLY- FieldDecorationRegistry API should specify that null dec description is allowed
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/FieldDecorationRegistry.java
* Get the maximum width (in pixels) of any decoration retrieved so far in
	 * the registry. This value changes as decorations are added and retrieved.
	 * This value can be used by clients to reserve space or otherwise compute
	 * margins when aligning non-decorated fields with decorated fields.
	 * 
	 * @return the maximum width in pixels of any accessed decoration
	 */
	public int getMaximumDecorationWidth() {
		return maxDecorationWidth;
	}
	/**
	 * Get the maximum height (in pixels) of any decoration retrieved so far in
	 * the registry. This value changes as decorations are added and retrieved.
	 * This value can be used by clients to reserve space or otherwise compute
	 * margins when aligning non-decorated fields with decorated fields.
	 * 
	 * 
	 * @return the maximum height in pixels of any accessed decoration
	 */
	public int getMaximumDecorationHeight() {
		return maxDecorationHeight;
	}
	/**
	 * Registers a field decoration using the specified id. The lifecyle of the
	 * supplied image should be managed by the client. That is, it will never be
	 * disposed by this registry and the decoration should be removed from the
	 * registry if the image is ever disposed elsewhere.
	 * 
	 * @param id
	 *            the String id used to identify and access the decoration.