Bug 214137 [Markers] Unbound system filters should be bound to problems view.
In 3.3 we supported systemFilters which are not currently picked up by the problems view. We should pick these up for compatiblity.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/views/markers/PriorityMarkerFieldFilter.java
if (priority == null)
			return;
		selectedPriorities = priority.intValue();
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.ui.internal.provisional.views.markers.CompatibilityFieldFilter#loadLegacySettings(org.eclipse.ui.IMemento)
	 */
	public void loadLegacySettings(IMemento memento) {
		String setting = memento.getString(TaskFilter.TAG_PRIORITY);
		if (setting != null) {
			try {
				selectedPriorities = Integer.parseInt(setting);
			} catch (NumberFormatException eNumberFormat) {
			}
		}
		
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.ui.internal.provisional.views.markers.api.MarkerFieldFilter#saveSettings(org.eclipse.ui.IMemento)
	 */
	public void saveSettings(IMemento memento) {
		memento.putInteger(TAG_SELECTED_PRIORITIES, selectedPriorities);
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.ui.internal.provisional.views.markers.api.MarkerFieldFilter#select(org.eclipse.ui.internal.provisional.views.markers.api.MarkerItem)