Bug 61713 MessageDialog can't be created in non UI thread anymore
I20040511 In the past it was possible to create a MessageDialog from non UI threads. This is not possible with I20040511 anymore. Doing so now results in an invalid thread access to due the fact that the images are now managed by SWT.
bundles/org.eclipse.jface/src/org/eclipse/jface/resource/ImageRegistry.java
*/
	public void put(String key, ImageDescriptor descriptor) {
		Entry entry = getEntry(key);
		if (entry == null) {
			entry = new Entry();
			putEntry(key, entry);
		}
		if (entry.image == null) {
			entry.descriptor = descriptor;
			return;
		}
		throw new IllegalArgumentException("ImageRegistry key already in use: " + key); 
	}
	/**
	 * Adds an image to this registry.  This method fails if there
	 * is already an image or descriptor for the given key.
	 * <p>
	 * Note that an image registry owns all of the image objects registered
	 * with it, and automatically disposes of them when the SWT Display is disposed. 
	 * Because of this, clients must not register an image object
	 * that is managed by another object.
	 * </p>
	 *
	 * @param key the key
	 * @param image the image
	 * @exception IllegalArgumentException if the key already exists
	 */
	public void put(String key, Image image) {
		Entry entry = getEntry(key);
		if (entry == null) {