Bug 120544 [build path] Editing external source folder does not persist
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/BuildPathsBlock.java
folder.setSelection(fPageIndex);
		fCurrPage= (BuildPathBasePage) folder.getItem(fPageIndex).getData();
		folder.addSelectionListener(new SelectionAdapter() {
			public void widgetSelected(SelectionEvent e) {
				tabChanged(e.item);
			}	
		});
		fTabFolder= folder;
		PlatformUI.getWorkbench().getHelpSystem().setHelp(composite, IJavaHelpContextIds.BUILD_PATH_BLOCK);				
		Dialog.applyDialogFont(composite);
		return composite;
	}
	
	private Shell getShell() {
		if (fSWTWidget != null) {
			return fSWTWidget.getShell();
		}
		return JavaPlugin.getActiveWorkbenchShell();
	}
	
	/**
	 * Initializes the classpath for the given project. Multiple calls to init are allowed,
	 * but all existing settings will be cleared and replace by the given or default paths.
	 * @param jproject The java project to configure. Does not have to exist.
	 * @param outputLocation The output location to be set in the page. If <code>null</code>
	 * is passed, jdt default settings are used, or - if the project is an existing Java project- the
	 * output location of the existing project 
	 * @param classpathEntries The classpath entries to be set in the page. If <code>null</code>
	 * is passed, jdt default settings are used, or - if the project is an existing Java project - the