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/MarkerView.java
* 
			 * @see org.eclipse.swt.events.TreeAdapter#treeCollapsed(org.eclipse.swt.events.TreeEvent)
			 */
			public void treeCollapsed(TreeEvent e) {
				updateJob.removeExpandedCategory((MarkerCategory) e.item
						.getData());
			}
			/*
			 * (non-Javadoc)
			 * 
			 * @see org.eclipse.swt.events.TreeAdapter#treeExpanded(org.eclipse.swt.events.TreeEvent)
			 */
			public void treeExpanded(TreeEvent e) {
				updateJob
						.addExpandedCategory((MarkerCategory) e.item.getData());
			}
		});
		return tree;
	}
	/**
	 * The focus elements have changed. Update accordingly.
	 */
	private void refreshForFocusUpdate() {
		if (focusElements != null) {
			updateFilterSelection(focusElements);
			refreshViewer();
		}
	}
}