Bug 203838 [Markers] [Markers] clicking on column headers does not sort table
I20070918 Clicking on any of the column headers does not sort based on the relevant column.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/provisional/views/markers/MarkerContentGenerator.java
* Get the id of the perspective this content generator is the default for.
	 * 
	 * @return String or <code>null</code>.
	 */
	public String getDefaultPerspectiveId() {
		return configurationElement
				.getAttribute(ATTRIBUTE_DEFAULT_FOR_PERSPECTIVE);
	}
	/**
	 * Return the currently enabled filters.
	 * 
	 * @return Collection of MarkerFieldFilterGroup
	 */
	public Collection getEnabledFilters() {
		if (enabledFilters == null) {
			enabledFilters = new HashSet();
			Iterator filtersIterator = getAllFilters().iterator();
			while (filtersIterator.hasNext()) {
				MarkerFieldFilterGroup next = (MarkerFieldFilterGroup) filtersIterator
						.next();
				if (next.isEnabled())
					enabledFilters.add(next);
			}
		}
		return enabledFilters;
	}
	/**
	 * Return a collection of all of the configuration fields for this generator
	 * 
	 * @return Collection of {@link FilterConfigurationArea}