Bug 163461 [Field Assist] - API - ControlDecoration should work with image+text, not FieldDecoration
DecoratedField supported multiple decoration locations, so it was useful to expose a data structure that referred to a particular decoration. Hence FieldDecoration was defined. It is just an image+text data structure, but was useful for asking DecoratedField to "do things" to a particular decoration, such as hiding it, showing it, updating it, etc. The initial API for ControlDecoration also supported FieldDecoration, in an attempt to "explain itself" as being similar to DecoratedField. However, since a ControlDecoration only shows one decoration, there's not really a need for the image+text to have any kind of identity. It would be better if the ControlDecoration API worked in terms of having an image and a description text. Clients could still use FieldDecorations and the registry if desired, but the API shouldn't require it, since it's trivial to pull the image and text out of a decoration and feed it to ControlDecoration.
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ControlDecoration.java
*/
	public ControlDecoration(Control control, FieldDecoration decoration,
			int position) {
		this.position = position;
		this.decoration = decoration;
		this.control = control;
		addControlListeners();
	}
	/**
	 * Construct a ControlDecoration for decorating the specified control at the
	 * specified position. The decoration to be displayed will be specified at a
	 * later time.
	 * <p>
	 * SWT constants are used to specify the position of the decoration relative
	 * to the 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 control, and the constants
	 * <code>SWT.TOP</code>, <code>SWT.CENTER</code>, and
	 * <code>SWT.BOTTOM</code> describe the vertical alignment of the
	 * decoration relative to the control. Decorations always appear on either
	 * the left or right side of the control, 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 no position style bits are
	 * specified, the control decoration will be positioned to the left and
	 * center of the control (<code>SWT.LEFT | SWT.CENTER</code>).
	 * </p>
	 * 
	 * @param control
	 *            the control to be decorated