ui/src/main/java/ucar/nc2/ui/image/PictureCache.java
public static void stopBackgroundLoading() {
		Enumeration e = cacheLoadsInProgress.elements();
		while ( e.hasMoreElements() ) {
			((SourcePicture) e.nextElement()).stopLoading();
		}
	}
public static void stopBackgroundLoading() {
		Enumeration e = cacheLoadsInProgress.elements();
		while ( e.hasMoreElements() ) {
			((SourcePicture) e.nextElement()).stopLoading();
		}
	}
method to stop all background loading