Bug 208101 [Markers] Tasks content has mark completed enabled for non editable tasks
I20071030-0100 Mark completed is enabled for tasks that are not editable
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/provisional/views/markers/ExtendedMarkersView.java
/*
			 * (non-Javadoc)
			 * 
			 * @see org.eclipse.jface.viewers.ILazyTreeContentProvider#updateElement(java.lang.Object,
			 *      int)
			 */