Bug 167170 [Markers] Need to check for duplicate filter names
M3 It is currently possible to enter duplicate filter names
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/views/markers/internal/DialogMarkerFilter.java
ITableLabelProvider {
		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.jface.viewers.ITableLabelProvider#getColumnImage(java.lang.Object,
		 *      int)
		 */
		public Image getColumnImage(Object element, int columnIndex) {
			return null;
		}
		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.jface.viewers.ITableLabelProvider#getColumnText(java.lang.Object,
		 *      int)
		 */
		public String getColumnText(Object element, int columnIndex) {
			return ((AbstractNode) element).getName();
		}
	}
	/**
	 * Creates and manages a group of widgets for selecting a working set marker
	 * filter.
	 */
	private class WorkingSetGroup {