Bug 221521 [Markers] New markers API needs to be pared down
We have too much API in some of the new classes and they can be moved to internals
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/views/markers/ExtendedMarkersView.java
Collection allMarkers = new ArrayList();
		for (int i = 0; i < elements.length; i++) {
			addMarkers(elements[i], allMarkers);
		}
		IMarker[] markers = new IMarker[allMarkers.size()];
		allMarkers.toArray(markers);
		return markers;
	}
	/**
	 * Return the group used for categorisation.
	 * 
	 * @return MarkerGroup
	 */
	MarkerGroup getCategoryGroup() {
		return builder.getCategoryGroup();
	}
	/**
	 * Return the clipboard for the receiver.
	 * 
	 * @return Clipboard
	 */
	Clipboard getClipboard() {
		if (clipboard == null)
			clipboard = new Clipboard(viewer.getControl().getDisplay());
		return clipboard;
	}
	/**
	 * Return the content provider for the receiver.
	 * 
	 * @return ITreeContentProvider