Bug 127289 [Markers] SystemFilter and group selection state not preserved
We are not preserving the selection state of the system filters or which group is selected.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/views/markers/internal/MarkerFilter.java
* <b>Warning:</b> for internal package use only. Return the root marker
	 * types.
	 * 
	 * @return the root marker types.
	 */
	public List getRootTypes() {
		return rootTypes;
	}
	/**
	 * <b>Warning:</b> for internal package use only. Return the selected
	 * types.
	 * 
	 * @return the selected marker types to be displayed.
	 */
	public List getSelectedTypes() {
		return selectedTypes;
	}
	/**
	 * Find the typeModel entry that matches id.
	 * 
	 * @param id
	 *            the ID for a marker type
	 * @return MarkerType or <code>null</code> if it is not found.
	 */
	public MarkerType getMarkerType(String id) {
		return MarkerTypesModel.getInstance().getType(id);
	}
	/**
	 * @return the current working set or <code>null</code> if no working set
	 *         is defined.