Bug 214137 [Markers] Unbound system filters should be bound to problems view.
In 3.3 we supported systemFilters which are not currently picked up by the problems view. We should pick these up for compatiblity.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/views/markers/CachedMarkerBuilder.java
if (sorter.compareCategory(previous, elements[i]) != 0) {
					categories
							.add(new MarkerCategory(
									this,
									categoryStart,
									i - 1,
									getCategoryGroup()
											.getMarkerField()
											.getValue(
													markers
															.elementAt(categoryStart))));
					categoryStart = i;
				}
			}
			previous = elements[i];
		}
		if (end >= categoryStart) {
			categories.add(new MarkerCategory(this, categoryStart, end,
					getCategoryGroup().getMarkerField().getValue(
							markers.elementAt(categoryStart))));
		}
		MarkerCategory[] nodes = new MarkerCategory[categories.size()];
		categories.toArray(nodes);
		return nodes;
	}
	/**
	 * Cancel the pending jobs in the receiver.
	 */
	private void cancelJobs() {
		markerProcessJob.cancel();