Bug 49182 What should canceling setRawClasspath do ?
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/OptionsConfigurationBlock.java
monitor.beginTask("", 2); 
					try {
						if (fProject != null) {
							monitor.setTaskName(PreferencesMessages.getFormattedString("OptionsConfigurationBlock.buildproject.taskname", fProject.getElementName())); 
							fProject.getProject().build(IncrementalProjectBuilder.FULL_BUILD, new SubProgressMonitor(monitor,1));
							JavaPlugin.getWorkspace().build(IncrementalProjectBuilder.INCREMENTAL_BUILD, new SubProgressMonitor(monitor,1));
						} else {
							monitor.setTaskName(PreferencesMessages.getString("OptionsConfigurationBlock.buildall.taskname")); 
							JavaPlugin.getWorkspace().build(IncrementalProjectBuilder.FULL_BUILD, new SubProgressMonitor(monitor, 2));
						}
					} catch (CoreException e) {
						throw new InvocationTargetException(e);
					} finally {
						monitor.done();
					}
				}
			});
		} catch (InterruptedException e) {
			
		} catch (InvocationTargetException e) {
			String title= PreferencesMessages.getString("OptionsConfigurationBlock.builderror.title"); 
			String message= PreferencesMessages.getString("OptionsConfigurationBlock.builderror.message"); 
			ExceptionHandler.handle(e, getShell(), title, message);
		}
	}		
	
	public void performDefaults() {
		fWorkingValues= getDefaultOptions();
		updateControls();
		validateSettings(null, null);