Bug 155273 [Markers] Visibility of problems view columns should be configurable
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/views/markers/CachedMarkerBuilder.java
* (non-Javadoc)
			 * 
			 * @see org.eclipse.jface.util.IPropertyChangeListener#propertyChange(org.eclipse.jface.util.PropertyChangeEvent)
			 */
			public void propertyChange(PropertyChangeEvent event) {
				if (event.getProperty().equals(getMementoPreferenceName())) {
					rebuildFilters();
				}
			}
		};
		IDEWorkbenchPlugin.getDefault().getPreferenceStore()
				.addPropertyChangeListener(preferenceListener);
	}
	/**
	 * Return whether or not the receiver is building.
	 * 
	 * @return boolean
	 */
	public boolean isBuilding() {
		return building;
	}
	/**
	 * Return whether or not we are showing a hierarchy,.
	 * 
	 * @return <code>true</code> if a hierarchy is being shown.
	 */
	boolean isShowingHierarchy() {
		return categoryGroup != null;
	}
	/**