org.eclipse.ui.cheatsheets/src/org/eclipse/ui/internal/cheatsheets/dialogs/CheatSheetCategoryBasedSelectionDialog.java - platform/eclipse.platform.ua - Git at Google

 /*******************************************************************************
  * Copyright (c) 2002, 2004 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.cheatsheets.dialogs;


 import java.util.*;
 import java.util.List;

 import org.eclipse.core.runtime.Path;
 import org.eclipse.jface.dialogs.*;
 import org.eclipse.jface.dialogs.Dialog;
 import org.eclipse.jface.viewers.*;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.layout.*;
 import org.eclipse.swt.widgets.*;
 import org.eclipse.ui.dialogs.SelectionDialog;
 import org.eclipse.ui.model.*;

 import org.eclipse.ui.internal.cheatsheets.*;
 import org.eclipse.ui.internal.cheatsheets.registry.*;

 /**
  * Dialog to allow the user to select a cheat sheet from a list.
  */
 public class CheatSheetCategoryBasedSelectionDialog extends SelectionDialog implements ISelectionChangedListener {
 	private IDialogSettings settings;
 	private CheatSheetCollectionElement cheatsheetCategories;
 	private CheatSheetElement currentSelection;
 	private TreeViewer categoryTreeViewer;
 	private TableViewer cheatsheetSelectionViewer;
 	private final static int SIZING_CATEGORY_LIST_HEIGHT = 150;
 	private final static int SIZING_CATEGORY_LIST_WIDTH = 180;
 	private final static int SIZING_CHEATSHEET_LIST_HEIGHT = 150;
 	private final static int SIZING_CHEATSHEET_LIST_WIDTH = 350;
 	private boolean okButtonState;

 	// id constants
 	private final static String STORE_SELECTED_CATEGORY_ID =
 		"CheatSheetCategoryBasedSelectionDialog.STORE_SELECTED_CATEGORY_ID"; //$NON-NLS-1$
 	private final static String STORE_EXPANDED_CATEGORIES_ID =
 		"CheatSheetCategoryBasedSelectionDialog.STORE_EXPANDED_CATEGORIES_ID"; //$NON-NLS-1$
 	private final static String STORE_SELECTED_CHEATSHEET_ID =
 		"CheatSheetCategoryBasedSelectionDialog.STORE_SELECTED_CHEATSHEET_ID"; //$NON-NLS-1$

 	/**
 	 * Creates an instance of this dialog to display
 	 * the a list of cheat sheets.
 	 *
 	 * @param shell the parent shell
 	 */
 	public CheatSheetCategoryBasedSelectionDialog(Shell shell, CheatSheetCollectionElement cheatsheetCategories) {
 		super(shell);

 		this.cheatsheetCategories = cheatsheetCategories;

 		setTitle(Messages.CHEAT_SHEET_SELECTION_DIALOG_TITLE);
 		setMessage(Messages.CHEAT_SHEET_SELECTION_DIALOG_MSG);

 		setShellStyle(getShellStyle() | SWT.RESIZE);
 	}

 	/* (non-Javadoc)
 	 * Method declared on Window.
 	 */
 	protected void configureShell(Shell newShell) {
 		super.configureShell(newShell);
 		//  WorkbenchHelp.setHelp(newShell, IHelpContextIds.WELCOME_PAGE_SELECTION_DIALOG);
 	}

 	/* (non-Javadoc)
 	 * Method declared on Dialog.
 	 */
 	protected void createButtonsForButtonBar(Composite parent) {
 		super.createButtonsForButtonBar(parent);

 		enableOKButton(okButtonState);
 	}

 	/* (non-Javadoc)
 	 * Method declared on Dialog.
 	 */
 	protected Control createDialogArea(Composite parent) {
 		IDialogSettings workbenchSettings = CheatSheetPlugin.getPlugin().getDialogSettings();
 		IDialogSettings dialogSettings = workbenchSettings.getSection("CheatSheetCategoryBasedSelectionDialog");//$NON-NLS-1$
 		if(dialogSettings==null)
 			dialogSettings = workbenchSettings.addNewSection("CheatSheetCategoryBasedSelectionDialog");//$NON-NLS-1$

 		setDialogSettings(dialogSettings);

 		// top level group
 		Composite outerContainer = (Composite) super.createDialogArea(parent);
 		Layout layout = outerContainer.getLayout();
 		if(layout != null && layout instanceof GridLayout) {
 			((GridLayout)layout).numColumns = 2;
 		} else {
 			GridLayout gridLayout = new GridLayout();
 			outerContainer.setLayout(gridLayout);
 			outerContainer.setLayoutData(new GridData(GridData.FILL_BOTH));
 		}

 		// Create label
 		createMessageArea(outerContainer);

 		// category tree pane...create SWT tree directly to
 		// get single selection mode instead of multi selection.
 		Tree tree = new Tree(outerContainer, SWT.SINGLE | SWT.H_SCROLL | SWT.V_SCROLL | SWT.BORDER);
 		categoryTreeViewer = new TreeViewer(tree);
 		GridData data = new GridData(GridData.FILL_BOTH);
 		data.widthHint = SIZING_CATEGORY_LIST_WIDTH;
 		data.heightHint = SIZING_CATEGORY_LIST_HEIGHT;
 		categoryTreeViewer.getTree().setLayoutData(data);
 		categoryTreeViewer.setContentProvider(new BaseWorkbenchContentProvider());
 		categoryTreeViewer.setLabelProvider(new WorkbenchLabelProvider());
 		categoryTreeViewer.setSorter(CheatSheetCollectionSorter.INSTANCE);
 		categoryTreeViewer.addSelectionChangedListener(this);
 		categoryTreeViewer.setInput(cheatsheetCategories);

 		// cheatsheet actions pane...create SWT table directly to
 		// get single selection mode instead of multi selection.
 		Table table = new Table(outerContainer, SWT.SINGLE | SWT.H_SCROLL | SWT.V_SCROLL | SWT.BORDER);
 		cheatsheetSelectionViewer = new TableViewer(table);
 		data = new GridData(GridData.FILL_BOTH);
 		data.widthHint = SIZING_CHEATSHEET_LIST_WIDTH;
 		data.heightHint = SIZING_CHEATSHEET_LIST_HEIGHT;
 		cheatsheetSelectionViewer.getTable().setLayoutData(data);
 		cheatsheetSelectionViewer.setContentProvider(getCheatSheetProvider());
 		cheatsheetSelectionViewer.setLabelProvider(new WorkbenchLabelProvider());
 		cheatsheetSelectionViewer.addSelectionChangedListener(this);

 		// Add double-click listener
 		cheatsheetSelectionViewer.addDoubleClickListener(new IDoubleClickListener() {
 			public void doubleClick(DoubleClickEvent event) {
 				okPressed();
 			}
 		});

 		restoreWidgetValues();

 		if (!categoryTreeViewer.getSelection().isEmpty())
 			// we only set focus if a selection was restored
 			categoryTreeViewer.getTree().setFocus();

 		Dialog.applyDialogFont(outerContainer);
 		return outerContainer;
 	}

 	/**
 	 * @see org.eclipse.ui.dialogs.SelectionDialog#createMessageArea(Composite)
 	 */
 	protected Label createMessageArea(Composite composite) {
 		Label label = new Label(composite,SWT.NONE);
 		label.setText(getMessage());

 		GridData gridData = new GridData(GridData.FILL_HORIZONTAL | GridData.VERTICAL_ALIGN_FILL);
 		gridData.horizontalSpan = 2;
 		label.setLayoutData(gridData);

 		return label;
 	}

 	/**
 	 * Method enableOKButton enables/diables the OK button for the dialog
 	 * and saves the state, allowing the enabling/disabling to occur even if
 	 * the button has not been created yet.
 	 *
 	 * @param value
 	 */
 	private void enableOKButton(boolean value) {
 		Button button = getButton(IDialogConstants.OK_ID);

 		okButtonState = value;
 		if( button != null ) {
 			button.setEnabled(value);
 		}
 	}

 	/**
 	 * Expands the cheatsheet categories in this page's category viewer that were
 	 * expanded last time this page was used.  If a category that was previously
 	 * expanded no longer exists then it is ignored.
 	 */
 	protected void expandPreviouslyExpandedCategories() {
 		String[] expandedCategoryPaths = settings.getArray(STORE_EXPANDED_CATEGORIES_ID);
 		List categoriesToExpand = new ArrayList(expandedCategoryPaths.length);

 		for (int i = 0; i < expandedCategoryPaths.length; i++){
 			CheatSheetCollectionElement category =
 				cheatsheetCategories.findChildCollection(
 					new Path(expandedCategoryPaths[i]));
 			if (category != null)	// ie.- it still exists
 				categoriesToExpand.add(category);
 		}

 		if (!categoriesToExpand.isEmpty())
 			categoryTreeViewer.setExpandedElements(categoriesToExpand.toArray());
 	}

 	/**
 	 * Returns the content provider for this page.
 	 */
 	protected IContentProvider getCheatSheetProvider() {
 		//want to get the cheatsheets of the collection element
 		return new BaseWorkbenchContentProvider() {
 			public Object[] getChildren(Object o) {
 				if (o instanceof CheatSheetCollectionElement) {
 					return ((CheatSheetCollectionElement)o).getCheatSheets();
 				}
 				return new Object[0];
 			}
 		};
 	}

 	/**
 	 * Returns the single selected object contained in the passed selectionEvent,
 	 * or <code>null</code> if the selectionEvent contains either 0 or 2+ selected
 	 * objects.
 	 */
 	protected Object getSingleSelection(IStructuredSelection selection) {
 		return selection.size() == 1 ? selection.getFirstElement() : null;
 	}

 	/**
 	 *	Handle the (de)selection of cheatsheet element(s)
 	 *
 	 * @param selectionEvent SelectionChangedEvent
 	 */
 	private void handleCategorySelection(SelectionChangedEvent selectionEvent) {
 		Object selection = cheatsheetSelectionViewer.getInput();
 		Object selectedCategory =
 			getSingleSelection((IStructuredSelection)selectionEvent.getSelection());
 		if (selection != selectedCategory) {
 			cheatsheetSelectionViewer.setInput(selectedCategory);

 			enableOKButton(false);
 		}
 	}

 	/**
 	 *	Handle the (de)selection of cheatsheet element(s)
 	 *
 	 *	@param selectionEvent SelectionChangedEvent
 	 */
 	private void handleCheatSheetSelection(SelectionChangedEvent selectionEvent) {
 		currentSelection = (CheatSheetElement)getSingleSelection((IStructuredSelection)selectionEvent.getSelection());

 		if( currentSelection != null ) {
 			enableOKButton(true);
 		}
 	}

 	/* (non-Javadoc)
 	 * Method declared on Dialog.
 	 */
 	protected void okPressed() {
 		if( currentSelection != null ) {
 			ArrayList result = new ArrayList(1);
 			result.add(currentSelection);
 			setResult(result);
 		} else {
 			return;
 		}

 		//save our selection state
 		saveWidgetValues();

 		super.okPressed();
 	}

 	/**
 	 *	Set self's widgets to the values that they held last time this page was open
 	 *
 	 */
 	protected void restoreWidgetValues() {
 		String[] expandedCategoryPaths = settings.getArray(STORE_EXPANDED_CATEGORIES_ID);
 		if (expandedCategoryPaths == null)
 			return;				// no stored values

 		expandPreviouslyExpandedCategories();
 		selectPreviouslySelectedCategoryAndCheatSheet();
 	}

 	/**
 	 *	Store the current values of self's widgets so that they can
 	 *	be restored in the next instance of self
 	 *
 	 */
 	public void saveWidgetValues() {
 		storeExpandedCategories();
 		storeSelectedCategoryAndCheatSheet();
 	}

 	/**
 	 *	The user selected either new cheatsheet category(s) or cheatsheet element(s).
 	 *	Proceed accordingly.
 	 *
 	 *	@param newSelection ISelection
 	 */
 	public void selectionChanged(SelectionChangedEvent selectionEvent) {
 		if (selectionEvent.getSelectionProvider().equals(categoryTreeViewer))
 			handleCategorySelection(selectionEvent);
 		else
 			handleCheatSheetSelection(selectionEvent);
 	}

 	/**
 	 * Selects the cheatsheet category and cheatsheet in this page that were selected
 	 * last time this page was used.  If a category or cheatsheet that was previously
 	 * selected no longer exists then it is ignored.
 	 */
 	protected void selectPreviouslySelectedCategoryAndCheatSheet() {
 		String categoryId = settings.get(STORE_SELECTED_CATEGORY_ID);
 		if (categoryId == null)
 			return;
 		CheatSheetCollectionElement category =
 			cheatsheetCategories.findChildCollection(new Path(categoryId));
 		if (category == null)
 			return;				// category no longer exists, or has moved

 		StructuredSelection selection = new StructuredSelection(category);
 		categoryTreeViewer.setSelection(selection);
 		selectionChanged(new SelectionChangedEvent(categoryTreeViewer,selection));

 		String cheatsheetId = settings.get(STORE_SELECTED_CHEATSHEET_ID);
 		if (cheatsheetId == null)
 			return;
 		CheatSheetElement cheatsheet = category.findCheatSheet(cheatsheetId,false);
 		if (cheatsheet == null)
 			return;				// cheatsheet no longer exists, or has moved

 		selection = new StructuredSelection(cheatsheet);
 		cheatsheetSelectionViewer.setSelection(selection);
 		selectionChanged(new SelectionChangedEvent(cheatsheetSelectionViewer,selection));
 	}

 	/**
 	 *	Set the dialog store to use for widget value storage and retrieval
 	 *
 	 *	@param settings IDialogSettings
 	 */
 	public void setDialogSettings(IDialogSettings settings) {
 		this.settings = settings;
 	}

 	/**
 	 * Stores the collection of currently-expanded categories in this page's dialog store,
 	 * in order to recreate this page's state in the next instance of this page.
 	 */
 	protected void storeExpandedCategories() {
 		Object[] expandedElements = categoryTreeViewer.getExpandedElements();
 		String[] expandedElementPaths = new String[expandedElements.length];
 		for (int i = 0; i < expandedElements.length; ++i) {
 			expandedElementPaths[i] =
 				((CheatSheetCollectionElement)expandedElements[i]).getPath().toString();
 		}
 		settings.put(
 			STORE_EXPANDED_CATEGORIES_ID,
 			expandedElementPaths);
 	}

 	/**
 	 * Stores the currently-selected category and cheatsheet in this page's dialog store,
 	 * in order to recreate this page's state in the next instance of this page.
 	 */
 	protected void storeSelectedCategoryAndCheatSheet() {
 		CheatSheetCollectionElement selectedCategory = (CheatSheetCollectionElement)
 			getSingleSelection((IStructuredSelection)categoryTreeViewer.getSelection());

 		if (selectedCategory != null) {
 			settings.put(
 				STORE_SELECTED_CATEGORY_ID,
 				selectedCategory.getPath().toString());
 		}

 		CheatSheetElement selectedCheatSheet = (CheatSheetElement)
 			getSingleSelection((IStructuredSelection)cheatsheetSelectionViewer.getSelection());

 		if (selectedCheatSheet != null) {
 			settings.put(
 				STORE_SELECTED_CHEATSHEET_ID,
 				selectedCheatSheet.getID());
 		}
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2002, 2004 IBM Corporation and others.
	* All rights reserved. This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License v1.0
	* which accompanies this distribution, and is available at
	* http://www.eclipse.org/legal/epl-v10.html
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/
	package org.eclipse.ui.internal.cheatsheets.dialogs;


	import java.util.*;
	import java.util.List;

	import org.eclipse.core.runtime.Path;
	import org.eclipse.jface.dialogs.*;
	import org.eclipse.jface.dialogs.Dialog;
	import org.eclipse.jface.viewers.*;
	import org.eclipse.swt.SWT;
	import org.eclipse.swt.layout.*;
	import org.eclipse.swt.widgets.*;
	import org.eclipse.ui.dialogs.SelectionDialog;
	import org.eclipse.ui.model.*;

	import org.eclipse.ui.internal.cheatsheets.*;
	import org.eclipse.ui.internal.cheatsheets.registry.*;

	/**
	* Dialog to allow the user to select a cheat sheet from a list.
	*/
	public class CheatSheetCategoryBasedSelectionDialog extends SelectionDialog implements ISelectionChangedListener {
	private IDialogSettings settings;
	private CheatSheetCollectionElement cheatsheetCategories;
	private CheatSheetElement currentSelection;
	private TreeViewer categoryTreeViewer;
	private TableViewer cheatsheetSelectionViewer;
	private final static int SIZING_CATEGORY_LIST_HEIGHT = 150;
	private final static int SIZING_CATEGORY_LIST_WIDTH = 180;
	private final static int SIZING_CHEATSHEET_LIST_HEIGHT = 150;
	private final static int SIZING_CHEATSHEET_LIST_WIDTH = 350;
	private boolean okButtonState;

	// id constants
	private final static String STORE_SELECTED_CATEGORY_ID =
	"CheatSheetCategoryBasedSelectionDialog.STORE_SELECTED_CATEGORY_ID"; //$NON-NLS-1$
	private final static String STORE_EXPANDED_CATEGORIES_ID =
	"CheatSheetCategoryBasedSelectionDialog.STORE_EXPANDED_CATEGORIES_ID"; //$NON-NLS-1$
	private final static String STORE_SELECTED_CHEATSHEET_ID =
	"CheatSheetCategoryBasedSelectionDialog.STORE_SELECTED_CHEATSHEET_ID"; //$NON-NLS-1$

	/**
	* Creates an instance of this dialog to display
	* the a list of cheat sheets.
	*
	* @param shell the parent shell
	*/
	public CheatSheetCategoryBasedSelectionDialog(Shell shell, CheatSheetCollectionElement cheatsheetCategories) {
	super(shell);

	this.cheatsheetCategories = cheatsheetCategories;

	setTitle(Messages.CHEAT_SHEET_SELECTION_DIALOG_TITLE);
	setMessage(Messages.CHEAT_SHEET_SELECTION_DIALOG_MSG);

	setShellStyle(getShellStyle() \| SWT.RESIZE);
	}

	/* (non-Javadoc)
	* Method declared on Window.
	*/
	protected void configureShell(Shell newShell) {
	super.configureShell(newShell);
	// WorkbenchHelp.setHelp(newShell, IHelpContextIds.WELCOME_PAGE_SELECTION_DIALOG);
	}

	/* (non-Javadoc)
	* Method declared on Dialog.
	*/
	protected void createButtonsForButtonBar(Composite parent) {
	super.createButtonsForButtonBar(parent);

	enableOKButton(okButtonState);
	}

	/* (non-Javadoc)
	* Method declared on Dialog.
	*/
	protected Control createDialogArea(Composite parent) {
	IDialogSettings workbenchSettings = CheatSheetPlugin.getPlugin().getDialogSettings();
	IDialogSettings dialogSettings = workbenchSettings.getSection("CheatSheetCategoryBasedSelectionDialog");//$NON-NLS-1$
	if(dialogSettings==null)
	dialogSettings = workbenchSettings.addNewSection("CheatSheetCategoryBasedSelectionDialog");//$NON-NLS-1$

	setDialogSettings(dialogSettings);

	// top level group
	Composite outerContainer = (Composite) super.createDialogArea(parent);
	Layout layout = outerContainer.getLayout();
	if(layout != null && layout instanceof GridLayout) {
	((GridLayout)layout).numColumns = 2;
	} else {
	GridLayout gridLayout = new GridLayout();
	outerContainer.setLayout(gridLayout);
	outerContainer.setLayoutData(new GridData(GridData.FILL_BOTH));
	}

	// Create label
	createMessageArea(outerContainer);

	// category tree pane...create SWT tree directly to
	// get single selection mode instead of multi selection.
	Tree tree = new Tree(outerContainer, SWT.SINGLE \| SWT.H_SCROLL \| SWT.V_SCROLL \| SWT.BORDER);
	categoryTreeViewer = new TreeViewer(tree);
	GridData data = new GridData(GridData.FILL_BOTH);
	data.widthHint = SIZING_CATEGORY_LIST_WIDTH;
	data.heightHint = SIZING_CATEGORY_LIST_HEIGHT;
	categoryTreeViewer.getTree().setLayoutData(data);
	categoryTreeViewer.setContentProvider(new BaseWorkbenchContentProvider());
	categoryTreeViewer.setLabelProvider(new WorkbenchLabelProvider());
	categoryTreeViewer.setSorter(CheatSheetCollectionSorter.INSTANCE);
	categoryTreeViewer.addSelectionChangedListener(this);
	categoryTreeViewer.setInput(cheatsheetCategories);

	// cheatsheet actions pane...create SWT table directly to
	// get single selection mode instead of multi selection.
	Table table = new Table(outerContainer, SWT.SINGLE \| SWT.H_SCROLL \| SWT.V_SCROLL \| SWT.BORDER);
	cheatsheetSelectionViewer = new TableViewer(table);
	data = new GridData(GridData.FILL_BOTH);
	data.widthHint = SIZING_CHEATSHEET_LIST_WIDTH;
	data.heightHint = SIZING_CHEATSHEET_LIST_HEIGHT;
	cheatsheetSelectionViewer.getTable().setLayoutData(data);
	cheatsheetSelectionViewer.setContentProvider(getCheatSheetProvider());
	cheatsheetSelectionViewer.setLabelProvider(new WorkbenchLabelProvider());
	cheatsheetSelectionViewer.addSelectionChangedListener(this);

	// Add double-click listener
	cheatsheetSelectionViewer.addDoubleClickListener(new IDoubleClickListener() {
	public void doubleClick(DoubleClickEvent event) {
	okPressed();
	}
	});

	restoreWidgetValues();

	if (!categoryTreeViewer.getSelection().isEmpty())
	// we only set focus if a selection was restored
	categoryTreeViewer.getTree().setFocus();

	Dialog.applyDialogFont(outerContainer);
	return outerContainer;
	}

	/**
	* @see org.eclipse.ui.dialogs.SelectionDialog#createMessageArea(Composite)
	*/
	protected Label createMessageArea(Composite composite) {
	Label label = new Label(composite,SWT.NONE);
	label.setText(getMessage());

	GridData gridData = new GridData(GridData.FILL_HORIZONTAL \| GridData.VERTICAL_ALIGN_FILL);
	gridData.horizontalSpan = 2;
	label.setLayoutData(gridData);

	return label;
	}

	/**
	* Method enableOKButton enables/diables the OK button for the dialog
	* and saves the state, allowing the enabling/disabling to occur even if
	* the button has not been created yet.
	*
	* @param value
	*/
	private void enableOKButton(boolean value) {
	Button button = getButton(IDialogConstants.OK_ID);

	okButtonState = value;
	if( button != null ) {
	button.setEnabled(value);
	}
	}

	/**
	* Expands the cheatsheet categories in this page's category viewer that were
	* expanded last time this page was used. If a category that was previously
	* expanded no longer exists then it is ignored.
	*/
	protected void expandPreviouslyExpandedCategories() {
	String[] expandedCategoryPaths = settings.getArray(STORE_EXPANDED_CATEGORIES_ID);
	List categoriesToExpand = new ArrayList(expandedCategoryPaths.length);

	for (int i = 0; i < expandedCategoryPaths.length; i++){
	CheatSheetCollectionElement category =
	cheatsheetCategories.findChildCollection(
	new Path(expandedCategoryPaths[i]));
	if (category != null) // ie.- it still exists
	categoriesToExpand.add(category);
	}

	if (!categoriesToExpand.isEmpty())
	categoryTreeViewer.setExpandedElements(categoriesToExpand.toArray());
	}

	/**
	* Returns the content provider for this page.
	*/
	protected IContentProvider getCheatSheetProvider() {
	//want to get the cheatsheets of the collection element
	return new BaseWorkbenchContentProvider() {
	public Object[] getChildren(Object o) {
	if (o instanceof CheatSheetCollectionElement) {
	return ((CheatSheetCollectionElement)o).getCheatSheets();
	}
	return new Object[0];
	}
	};
	}

	/**
	* Returns the single selected object contained in the passed selectionEvent,
	* or <code>null</code> if the selectionEvent contains either 0 or 2+ selected
	* objects.
	*/
	protected Object getSingleSelection(IStructuredSelection selection) {
	return selection.size() == 1 ? selection.getFirstElement() : null;
	}

	/**
	* Handle the (de)selection of cheatsheet element(s)
	*
	* @param selectionEvent SelectionChangedEvent
	*/
	private void handleCategorySelection(SelectionChangedEvent selectionEvent) {
	Object selection = cheatsheetSelectionViewer.getInput();
	Object selectedCategory =
	getSingleSelection((IStructuredSelection)selectionEvent.getSelection());
	if (selection != selectedCategory) {
	cheatsheetSelectionViewer.setInput(selectedCategory);

	enableOKButton(false);
	}
	}

	/**
	* Handle the (de)selection of cheatsheet element(s)
	*
	* @param selectionEvent SelectionChangedEvent
	*/
	private void handleCheatSheetSelection(SelectionChangedEvent selectionEvent) {
	currentSelection = (CheatSheetElement)getSingleSelection((IStructuredSelection)selectionEvent.getSelection());

	if( currentSelection != null ) {
	enableOKButton(true);
	}
	}

	/* (non-Javadoc)
	* Method declared on Dialog.
	*/
	protected void okPressed() {
	if( currentSelection != null ) {
	ArrayList result = new ArrayList(1);
	result.add(currentSelection);
	setResult(result);
	} else {
	return;
	}

	//save our selection state
	saveWidgetValues();

	super.okPressed();
	}

	/**
	* Set self's widgets to the values that they held last time this page was open
	*
	*/
	protected void restoreWidgetValues() {
	String[] expandedCategoryPaths = settings.getArray(STORE_EXPANDED_CATEGORIES_ID);
	if (expandedCategoryPaths == null)
	return; // no stored values

	expandPreviouslyExpandedCategories();
	selectPreviouslySelectedCategoryAndCheatSheet();
	}

	/**
	* Store the current values of self's widgets so that they can
	* be restored in the next instance of self
	*
	*/
	public void saveWidgetValues() {
	storeExpandedCategories();
	storeSelectedCategoryAndCheatSheet();
	}

	/**
	* The user selected either new cheatsheet category(s) or cheatsheet element(s).
	* Proceed accordingly.
	*
	* @param newSelection ISelection
	*/
	public void selectionChanged(SelectionChangedEvent selectionEvent) {
	if (selectionEvent.getSelectionProvider().equals(categoryTreeViewer))
	handleCategorySelection(selectionEvent);
	else
	handleCheatSheetSelection(selectionEvent);
	}

	/**
	* Selects the cheatsheet category and cheatsheet in this page that were selected
	* last time this page was used. If a category or cheatsheet that was previously
	* selected no longer exists then it is ignored.
	*/
	protected void selectPreviouslySelectedCategoryAndCheatSheet() {
	String categoryId = settings.get(STORE_SELECTED_CATEGORY_ID);
	if (categoryId == null)
	return;
	CheatSheetCollectionElement category =
	cheatsheetCategories.findChildCollection(new Path(categoryId));
	if (category == null)
	return; // category no longer exists, or has moved

	StructuredSelection selection = new StructuredSelection(category);
	categoryTreeViewer.setSelection(selection);
	selectionChanged(new SelectionChangedEvent(categoryTreeViewer,selection));

	String cheatsheetId = settings.get(STORE_SELECTED_CHEATSHEET_ID);
	if (cheatsheetId == null)
	return;
	CheatSheetElement cheatsheet = category.findCheatSheet(cheatsheetId,false);
	if (cheatsheet == null)
	return; // cheatsheet no longer exists, or has moved

	selection = new StructuredSelection(cheatsheet);
	cheatsheetSelectionViewer.setSelection(selection);
	selectionChanged(new SelectionChangedEvent(cheatsheetSelectionViewer,selection));
	}

	/**
	* Set the dialog store to use for widget value storage and retrieval
	*
	* @param settings IDialogSettings
	*/
	public void setDialogSettings(IDialogSettings settings) {
	this.settings = settings;
	}

	/**
	* Stores the collection of currently-expanded categories in this page's dialog store,
	* in order to recreate this page's state in the next instance of this page.
	*/
	protected void storeExpandedCategories() {
	Object[] expandedElements = categoryTreeViewer.getExpandedElements();
	String[] expandedElementPaths = new String[expandedElements.length];
	for (int i = 0; i < expandedElements.length; ++i) {
	expandedElementPaths[i] =
	((CheatSheetCollectionElement)expandedElements[i]).getPath().toString();
	}
	settings.put(
	STORE_EXPANDED_CATEGORIES_ID,
	expandedElementPaths);
	}

	/**
	* Stores the currently-selected category and cheatsheet in this page's dialog store,
	* in order to recreate this page's state in the next instance of this page.
	*/
	protected void storeSelectedCategoryAndCheatSheet() {
	CheatSheetCollectionElement selectedCategory = (CheatSheetCollectionElement)
	getSingleSelection((IStructuredSelection)categoryTreeViewer.getSelection());

	if (selectedCategory != null) {
	settings.put(
	STORE_SELECTED_CATEGORY_ID,
	selectedCategory.getPath().toString());
	}

	CheatSheetElement selectedCheatSheet = (CheatSheetElement)
	getSingleSelection((IStructuredSelection)cheatsheetSelectionViewer.getSelection());

	if (selectedCheatSheet != null) {
	settings.put(
	STORE_SELECTED_CHEATSHEET_ID,
	selectedCheatSheet.getID());
	}
	}
	}