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
*/
	IWorkingSet getWorkingSet() {
		return workingSet;
	}
	/**
	 * Sets the enablement state of the filter.
	 */
	void setEnabled(boolean enabled) {
		this.enabled = enabled;
	}
	/**
	 * Sets the current working set.
	 */
	void setWorkingSet(IWorkingSet workingSet) {
		this.workingSet = workingSet;
		cachedWorkingSet = null;
	}
	/**
	 * Reset to the default state.
	 */
	void resetState() {
		enabled = DEFAULT_ACTIVATION_STATUS;
		onResource = DEFAULT_ON_RESOURCE;
		selectedTypes.clear();
		addAllSubTypes(selectedTypes);
		setWorkingSet(null);
	}
	/**
	 * Restore the state in the memento.
	 *