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
* @return the image, or <code>null</code> if none
	 */
	public Image get(String key) {
		
		if (key == null){
			return null;
		}
		/**
		 * NOTE, for backwards compatibility the following images are supported
		 * here, they should never be disposed, hence we explicitly return them 
		 * rather then registering images that SWT will dispose.  
		 * 
		 * Applications should go direclty to SWT for these icons.
		 * 
		 * @see Display.getSystemIcon(int ID)
		 */
		if (key.equals(Dialog.DLG_IMG_INFO)) {
			return Display.getCurrent().getSystemImage(SWT.ICON_INFORMATION);
		}
		if (key.equals(Dialog.DLG_IMG_QUESTION)) {
			return Display.getCurrent().getSystemImage(SWT.ICON_QUESTION);
		}
		if (key.equals(Dialog.DLG_IMG_WARNING)) {
			return Display.getCurrent().getSystemImage(SWT.ICON_WARNING);
		}
		if (key.equals(Dialog.DLG_IMG_ERROR)) {
				return Display.getCurrent().getSystemImage(SWT.ICON_ERROR);
		}
		
		Entry entry = getEntry(key);