Bug 155273 [Markers] Visibility of problems view columns should be configurable
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/views/markers/ExtendedMarkersView.java
memento.putString(TAG_PART_NAME, getPartName());
		if (!getCategoriesToExpand().isEmpty()) {
			IMemento expanded = memento.createChild(TAG_EXPANDED);
			Iterator categories = getCategoriesToExpand().iterator();
			while (categories.hasNext()) {
				expanded.createChild(TAG_CATEGORY, (String) categories.next());
			}
		}
		builder.saveState(memento);
		IMemento columnEntry = memento.createChild(TAG_COLUMN_WIDTHS);
		TreeColumn[] columns = viewer.getTree().getColumns();
		for (int i = 0; i < columns.length; i++) {
			columnEntry.putInteger(getFieldId(columns[i]), columns[i]
					.getWidth());
		}
	}
	/**
	 * Select all of the elements in the receiver.
	 */
	void selectAll() {
		viewer.getTree().selectAll();
	}
	/**
	 * Set the category group for the receiver.
	 * 
	 * @param group
	 */
	void setCategoryGroup(MarkerGroup group) {
		getCategoriesToExpand().clear();
		builder.setCategoryGroup(group);