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
*/
	private void addMarkers(MarkerItem markerItem, Collection allMarkers) {
		if (markerItem.getMarker() != null)
			allMarkers.add(markerItem.getMarker());
		MarkerItem[] children = markerItem.getChildren();
		for (int i = 0; i < children.length; i++) {
			addMarkers(children[i], allMarkers);
		}
	}
	/**
	 * Create the columns for the receiver.
	 * 
	 * @param currentColumns
	 *            the columns to refresh
	 */
	private void createColumns(TreeColumn[] currentColumns) {
		Tree tree = viewer.getTree();
		TableLayout layout = new TableLayout();
		MarkerField[] fields = builder.getGenerator().getVisibleFields();
		for (int i = 0; i < fields.length; i++) {
			MarkerField markerField = fields[i];
			
			int columnWidth = markerField.getDefaultColumnWidth(tree);
			if (i == 0) {
				
				GC gc = new GC(tree);
				gc.setFont(tree.getFont());
				FontMetrics fontMetrics = gc.getFontMetrics();
				gc.dispose();
				columnWidth = Math.max(columnWidth, fontMetrics