bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/dialogs/PathVariablesGroup.java - platform/eclipse.platform.ui - Git at Google

 /************************************************************************
 Copyright (c) 2000, 2002 IBM Corporation and others.
 All rights reserved.   This program and the accompanying materials
 are made available under the terms of the Common Public License v1.0
 which accompanies this distribution, and is available at
 http://www.eclipse.org/legal/cpl-v10.html

 Contributors:
     IBM - Initial implementation
 ************************************************************************/
 package org.eclipse.ui.internal.dialogs;

 import java.io.File;
 import java.util.*;

 import org.eclipse.core.resources.*;
 import org.eclipse.core.runtime.*;
 import org.eclipse.jface.dialogs.*;
 import org.eclipse.jface.dialogs.Dialog;
 import org.eclipse.jface.resource.ImageDescriptor;
 import org.eclipse.jface.window.Window;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.SelectionAdapter;
 import org.eclipse.swt.events.SelectionEvent;
 import org.eclipse.swt.graphics.*;
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.layout.GridLayout;
 import org.eclipse.swt.widgets.*;
 import org.eclipse.ui.ISharedImages;
 import org.eclipse.ui.PlatformUI;
 import org.eclipse.ui.internal.WorkbenchImages;
 import org.eclipse.ui.internal.WorkbenchMessages;

 /**
  * A widget group that displays path variables.
  * Includes buttons to edit, remove existing variables and create new ones.
  *
  * @since 2.1
  */
 public class PathVariablesGroup {
 	// sizing constants
 	private static final int SIZING_SELECTION_PANE_WIDTH = 400;

 	// parent shell
 	private Shell shell;

 	private Table variableTable;
 	private Button addButton;
 	private Button editButton;
 	private Button removeButton;

 	// used to compute layout sizes
 	private FontMetrics fontMetrics;

 	// create a multi select table
 	private boolean multiSelect;
 	// IResource.FILE and/or IResource.FOLDER
 	private int variableType;
 	// temporary collection for keeping currently defined variables
 	private SortedMap tempPathVariables;
 	// set of removed variables' names
 	private Set removedVariableNames;
 	// reference to the workspace's path variable manager
 	private IPathVariableManager pathVariableManager;

 	// file image
 	private final Image FILE_IMG = WorkbenchImages.getImage(ISharedImages.IMG_OBJ_FILE);
 	// folder image
 	private final Image FOLDER_IMG = WorkbenchImages.getImage(ISharedImages.IMG_OBJ_FOLDER);
 	// unknown (non-existent) image. created locally, dispose locally
 	private Image imageUnkown;

 	/**
 	 * Creates a new PathVariablesGroup.
 	 *
 	 * @param multiSelect create a multi select tree
 	 * @param variableType the type of variables that are displayed in
 	 * 	the widget group. <code>IResource.FILE</code> and/or <code>IResource.FOLDER</code>
 	 * 	logically ORed together.
 	 */
 	public PathVariablesGroup(boolean multiSelect, int variableType) {
 		this.multiSelect = multiSelect;
 		this.variableType = variableType;
 		pathVariableManager = ResourcesPlugin.getWorkspace().getPathVariableManager();
 		removedVariableNames = new HashSet();
 		tempPathVariables = new TreeMap();
 		// initialize internal model
 		initTemporaryState();
 	}
 	/**
 	 * Opens a dialog for creating a new variable.
 	 */
 	private void addNewVariable() {
 		// constructs a dialog for editing the new variable's current name and value
 		PathVariableDialog dialog =
 			new PathVariableDialog(
 				shell,
 				PathVariableDialog.NEW_VARIABLE,
 				variableType,
 				pathVariableManager,
 				tempPathVariables.keySet());

 		// opens the dialog - just returns if the user cancels it
 		if (dialog.open() == Window.CANCEL)
 			return;

 		// otherwise, adds the new variable (or updates an existing one) in the
 		// temporary collection of currently defined variables
 		String newVariableName = dialog.getVariableName();
 		IPath newVariableValue = new Path(dialog.getVariableValue());
 		tempPathVariables.put(newVariableName, newVariableValue);

 		// the UI must be updated
 		updateWidgetState(newVariableName);
 	}
 	/**
 	 * Creates the widget group.
 	 * Callers must call <code>dispose</code> when the group is no
 	 * longer needed.
 	 *
 	 * @param parent the widget parent
 	 * @return container of the widgets
 	 */
 	public Control createContents(Composite parent) {
 		Font font = parent.getFont();

 		if (imageUnkown == null ) {
 			ImageDescriptor descriptor = WorkbenchImages.getImageDescriptorFromPluginID(
 				PlatformUI.PLUGIN_ID,
 				"icons/full/obj16/question.gif");	//$NON-NLS-1$
 			imageUnkown = descriptor.createImage();
 		}
 		initializeDialogUnits(parent);
 		shell = parent.getShell();

 		// define container & its layout
 		Composite pageComponent = new Composite(parent, SWT.NULL);
 		GridLayout layout = new GridLayout();
 		layout.numColumns = 2;
 		layout.marginWidth = 0;
 		layout.marginHeight = 0;
 		pageComponent.setLayout(layout);
 		GridData data = new GridData(GridData.FILL_BOTH);
 		data.widthHint = SIZING_SELECTION_PANE_WIDTH;
 		pageComponent.setLayoutData(data);
 		pageComponent.setFont(font);

 		// layout the table & its buttons
 		Label variableLabel = new Label(pageComponent, SWT.LEFT);
 		variableLabel.setText(WorkbenchMessages.getString("PathVariablesBlock.variablesLabel")); //$NON-NLS-1$
 		data = new GridData();
 		data.horizontalAlignment = GridData.FILL;
 		data.horizontalSpan = 2;
 		variableLabel.setLayoutData(data);
 		variableLabel.setFont(font);

 		int tableStyle = SWT.BORDER | SWT.FULL_SELECTION;
 		if (multiSelect) {
 			tableStyle |= SWT.MULTI;
 		}
 		variableTable = new Table(pageComponent, tableStyle);
 		variableTable.addSelectionListener(new SelectionAdapter() {
 			public void widgetSelected(SelectionEvent e) {
 				updateEnabledState();
 			}
 		});
 		data = new GridData(GridData.FILL_BOTH);
 		data.heightHint = variableTable.getItemHeight() * 7;
 		variableTable.setLayoutData(data);
 		variableTable.setFont(font);

 		createButtonGroup(pageComponent);
 		// populate table with current internal state and set buttons' initial state
 		updateWidgetState(null);

 		return pageComponent;
 	}
 	/**
 	 * Disposes the group's resources.
 	 */
 	public void dispose() {
 		if (imageUnkown != null) {
 			imageUnkown.dispose();
 			imageUnkown = null;
 		}
 	}
 	/**
 	 * Opens a dialog for editing an existing variable.
 	 *
 	 * @see PathVariableDialog
 	 */
 	private void editSelectedVariable() {
 		// retrieves the name and value for the currently selected variable
 		TableItem item = variableTable.getItem(variableTable.getSelectionIndex());
 		String variableName = (String) item.getData();
 		IPath variableValue = (IPath) tempPathVariables.get(variableName);

 		// constructs a dialog for editing the variable's current name and value
 		PathVariableDialog dialog =
 			new PathVariableDialog(
 				shell,
 				PathVariableDialog.EXISTING_VARIABLE,
 				variableType,
 				pathVariableManager,
 				tempPathVariables.keySet());
 		dialog.setVariableName(variableName);
 		dialog.setVariableValue(variableValue.toString());

 		// opens the dialog - just returns if the user cancels it
 		if (dialog.open() == Window.CANCEL)
 			return;

 		// the name can be changed, so we remove the current variable definition...
 		removedVariableNames.add(variableName);
 		tempPathVariables.remove(variableName);

 		String newVariableName = dialog.getVariableName();
 		IPath newVariableValue = new Path(dialog.getVariableValue());

 		// and add it again (maybe with a different name)
 		tempPathVariables.put(newVariableName, newVariableValue);

 		// now we must refresh the UI state
 		updateWidgetState(newVariableName);

 	}
 	/**
 	 * Returns the names of the selected variables.
 	 *
 	 * @return the names of the selected variables. Returns an empty
 	 * 	array if the widget group has not been created yet by calling
 	 * 	<code>createContents</code>
 	 */
 	public String[] getSelection() {
 		if (variableTable == null) {
 			return new String[0];
 		}
 		TableItem[] items = variableTable.getSelection();
 		String[] variableNames = new String[items.length];

 		for (int i = 0; i < items.length; i++) {
 			variableNames[i] = (String) items[i].getData();
 		}
 		return variableNames;
 	}
 	/**
 	 * Creates the add/edit/remove buttons
 	 *
 	 * @param parent the widget parent
 	 */
 	private void createButtonGroup(Composite parent) {
 		Font font = parent.getFont();
 		Composite groupComponent = new Composite(parent, SWT.NULL);
 		GridLayout groupLayout = new GridLayout();
 		groupLayout.marginWidth = 0;
 		groupLayout.marginHeight = 0;
 		groupComponent.setLayout(groupLayout);
 		GridData data = new GridData();
 		data.verticalAlignment = GridData.FILL;
 		data.horizontalAlignment = GridData.FILL;
 		groupComponent.setLayoutData(data);
 		groupComponent.setFont(font);

 		addButton = new Button(groupComponent, SWT.PUSH);
 		addButton.setText(WorkbenchMessages.getString("PathVariablesBlock.addVariableButton")); //$NON-NLS-1$
 		addButton.addSelectionListener(new SelectionAdapter() {
 			public void widgetSelected(SelectionEvent e) {
 				addNewVariable();
 			}
 		});
 		addButton.setFont(font);
 		setButtonLayoutData(addButton);

 		editButton = new Button(groupComponent, SWT.PUSH);
 		editButton.setText(WorkbenchMessages.getString("PathVariablesBlock.editVariableButton")); //$NON-NLS-1$
 		editButton.addSelectionListener(new SelectionAdapter() {
 			public void widgetSelected(SelectionEvent e) {
 				editSelectedVariable();
 			}
 		});
 		editButton.setFont(font);
 		setButtonLayoutData(editButton);

 		removeButton = new Button(groupComponent, SWT.PUSH);
 		removeButton.setText(WorkbenchMessages.getString("PathVariablesBlock.removeVariableButton")); //$NON-NLS-1$
 		removeButton.addSelectionListener(new SelectionAdapter() {
 			public void widgetSelected(SelectionEvent e) {
 				removeSelectedVariables();
 			}
 		});
 		removeButton.setFont(font);
 		setButtonLayoutData(removeButton);
 	}
 	/**
 	 * Initializes the computation of horizontal and vertical dialog units
 	 * based on the size of current font.
 	 * <p>
 	 * This method must be called before <code>setButtonLayoutData</code>
 	 * is called.
 	 * </p>
 	 *
 	 * @param control a control from which to obtain the current font
 	 */
 	protected void initializeDialogUnits(Control control) {
 		// Compute and store a font metric
 		GC gc = new GC(control);
 		gc.setFont(control.getFont());
 		fontMetrics = gc.getFontMetrics();
 		gc.dispose();
 	}
 	/**
 	 * (Re-)Initialize collections used to mantain temporary variable state.
 	 */
 	private void initTemporaryState() {
 		String[] varNames = pathVariableManager.getPathVariableNames();

 		tempPathVariables.clear();
 		for (int i = 0; i < varNames.length; i++) {
 			IPath value = pathVariableManager.getValue(varNames[i]);

 			// the value may not exist any more
 			if (value != null) {
 				boolean isFile = value.toFile().isFile();
 				if ((isFile && (variableType & IResource.FILE) != 0) ||
 				 	(isFile == false && (variableType & IResource.FOLDER) != 0)) {

 					tempPathVariables.put(varNames[i], value);
 				}
 			}
 		}
 		removedVariableNames.clear();
 	}
 	/**
 	 * Updates button enabled state, depending on the number of currently selected
 	 * variables in the table.
 	 */
 	private void updateEnabledState() {
 		int itemsSelectedCount = variableTable.getSelectionCount();
 		editButton.setEnabled(itemsSelectedCount == 1);
 		removeButton.setEnabled(itemsSelectedCount > 0);
 	}
 	/**
 	 * Rebuilds table widget state with the current list of variables (reflecting
 	 * any changes, additions and removals), and selects the item corresponding to
 	 * the given variable name. If the variable name is <code>null</code>, the
 	 * first item (if any) will be selected.
 	 *
 	 * @param selectedVarName the name for the variable to be selected (may be
 	 * <code>null</code>)
 	 * @see IPathVariableManager#getPathVariableNames()
 	 * @see IPathVariableManager#getValue(String)
 	 */
 	private void updateVariableTable(String selectedVarName) {
 		variableTable.removeAll();
 		int selectedVarIndex = 0;
 		for (Iterator varNames = tempPathVariables.keySet().iterator(); varNames.hasNext();) {
 			TableItem item = new TableItem(variableTable, SWT.NONE);
 			String varName = (String) varNames.next();
 			IPath value = (IPath) tempPathVariables.get(varName);
 			File file = value.toFile();

 			item.setText(varName + " - " + value.toString()); //$NON-NLS-1$
 			// the corresponding variable name is stored in each table widget item
 			item.setData(varName);
 			item.setImage(file.exists() ? (file.isFile() ? FILE_IMG : FOLDER_IMG) : imageUnkown);
 			if (varName.equals(selectedVarName))
 				selectedVarIndex = variableTable.getItemCount() - 1;
 		}
 		if (variableTable.getItemCount() > selectedVarIndex)
 			variableTable.setSelection(selectedVarIndex);
 	}
 	/**
 	 * Commits the temporary state to the path variable manager in response to user
 	 * confirmation.
 	 *
 	 * @see IPathVariableManager#setValue(String, IPath)
 	 */
 	public boolean performOk() {
 		try {
 			// first process removed variables
 			for (Iterator removed = removedVariableNames.iterator(); removed.hasNext();) {
 				String removedVariableName = (String) removed.next();
 				// only removes variables that have not been added again
 				if (!tempPathVariables.containsKey(removedVariableName))
 					pathVariableManager.setValue(removedVariableName, null);
 			}

 			// then process the current collection of variables, adding/updating them
 			for (Iterator current = tempPathVariables.entrySet().iterator(); current.hasNext();) {
 				Map.Entry entry = (Map.Entry) current.next();
 				String variableName = (String) entry.getKey();
 				IPath variableValue = (IPath) entry.getValue();
 				pathVariableManager.setValue(variableName, variableValue);
 			}
 			// re-initialize temporary state
 			initTemporaryState();

 			// performOk accepted
 			return true;
 		} catch (CoreException ce) {
 			ErrorDialog.openError(shell, null, null, ce.getStatus());
 		}
 		return false;
 	}
 	/**
 	 * Removes the currently selected variables.
 	 */
 	private void removeSelectedVariables() {
 		// remove each selected element
 		int[] selectedIndices = variableTable.getSelectionIndices();
 		for (int i = 0; i < selectedIndices.length; i++) {
 			TableItem selectedItem = variableTable.getItem(selectedIndices[i]);
 			String varName = (String) selectedItem.getData();
 			removedVariableNames.add(varName);
 			tempPathVariables.remove(varName);
 		}
 		updateWidgetState(null);
 	}
 	/**
 	 * Sets the <code>GridData</code> on the specified button to
 	 * be one that is spaced for the current dialog page units. The
 	 * method <code>initializeDialogUnits</code> must be called once
 	 * before calling this method for the first time.
 	 *
 	 * @param button the button to set the <code>GridData</code>
 	 * @return the <code>GridData</code> set on the specified button
 	 */
 	private GridData setButtonLayoutData(Button button) {
 		GridData data = new GridData(GridData.HORIZONTAL_ALIGN_FILL);
 		data.heightHint = Dialog.convertVerticalDLUsToPixels(fontMetrics, IDialogConstants.BUTTON_HEIGHT);
 		int widthHint = Dialog.convertHorizontalDLUsToPixels(fontMetrics, IDialogConstants.BUTTON_WIDTH);
 		data.widthHint = Math.max(widthHint, button.computeSize(SWT.DEFAULT, SWT.DEFAULT, true).x);
 		button.setLayoutData(data);
 		return data;
 	}
 	/**
 	 * Updates the widget's current state: refreshes the table with the current
 	 * defined variables, selects the item corresponding to the given variable
 	 * (selects the first item if <code>null</code> is provided) and updates
 	 * the enabled state for the Add/Remove/Edit buttons.
 	 *
 	 * @param selectedVarName the name of the variable to be selected (may be null)
 	 */
 	private void updateWidgetState(String selectedVarName) {
 		updateVariableTable(selectedVarName);
 		updateEnabledState();
 	}
 }
	/************************************************************************
	Copyright (c) 2000, 2002 IBM Corporation and others.
	All rights reserved. This program and the accompanying materials
	are made available under the terms of the Common Public License v1.0
	which accompanies this distribution, and is available at
	http://www.eclipse.org/legal/cpl-v10.html

	Contributors:
	IBM - Initial implementation
	************************************************************************/
	package org.eclipse.ui.internal.dialogs;

	import java.io.File;
	import java.util.*;

	import org.eclipse.core.resources.*;
	import org.eclipse.core.runtime.*;
	import org.eclipse.jface.dialogs.*;
	import org.eclipse.jface.dialogs.Dialog;
	import org.eclipse.jface.resource.ImageDescriptor;
	import org.eclipse.jface.window.Window;
	import org.eclipse.swt.SWT;
	import org.eclipse.swt.events.SelectionAdapter;
	import org.eclipse.swt.events.SelectionEvent;
	import org.eclipse.swt.graphics.*;
	import org.eclipse.swt.layout.GridData;
	import org.eclipse.swt.layout.GridLayout;
	import org.eclipse.swt.widgets.*;
	import org.eclipse.ui.ISharedImages;
	import org.eclipse.ui.PlatformUI;
	import org.eclipse.ui.internal.WorkbenchImages;
	import org.eclipse.ui.internal.WorkbenchMessages;

	/**
	* A widget group that displays path variables.
	* Includes buttons to edit, remove existing variables and create new ones.
	*
	* @since 2.1
	*/
	public class PathVariablesGroup {
	// sizing constants
	private static final int SIZING_SELECTION_PANE_WIDTH = 400;

	// parent shell
	private Shell shell;

	private Table variableTable;
	private Button addButton;
	private Button editButton;
	private Button removeButton;

	// used to compute layout sizes
	private FontMetrics fontMetrics;

	// create a multi select table
	private boolean multiSelect;
	// IResource.FILE and/or IResource.FOLDER
	private int variableType;
	// temporary collection for keeping currently defined variables
	private SortedMap tempPathVariables;
	// set of removed variables' names
	private Set removedVariableNames;
	// reference to the workspace's path variable manager
	private IPathVariableManager pathVariableManager;

	// file image
	private final Image FILE_IMG = WorkbenchImages.getImage(ISharedImages.IMG_OBJ_FILE);
	// folder image
	private final Image FOLDER_IMG = WorkbenchImages.getImage(ISharedImages.IMG_OBJ_FOLDER);
	// unknown (non-existent) image. created locally, dispose locally
	private Image imageUnkown;

	/**
	* Creates a new PathVariablesGroup.
	*
	* @param multiSelect create a multi select tree
	* @param variableType the type of variables that are displayed in
	* the widget group. <code>IResource.FILE</code> and/or <code>IResource.FOLDER</code>
	* logically ORed together.
	*/
	public PathVariablesGroup(boolean multiSelect, int variableType) {
	this.multiSelect = multiSelect;
	this.variableType = variableType;
	pathVariableManager = ResourcesPlugin.getWorkspace().getPathVariableManager();
	removedVariableNames = new HashSet();
	tempPathVariables = new TreeMap();
	// initialize internal model
	initTemporaryState();
	}
	/**
	* Opens a dialog for creating a new variable.
	*/
	private void addNewVariable() {
	// constructs a dialog for editing the new variable's current name and value
	PathVariableDialog dialog =
	new PathVariableDialog(
	shell,
	PathVariableDialog.NEW_VARIABLE,
	variableType,
	pathVariableManager,
	tempPathVariables.keySet());

	// opens the dialog - just returns if the user cancels it
	if (dialog.open() == Window.CANCEL)
	return;

	// otherwise, adds the new variable (or updates an existing one) in the
	// temporary collection of currently defined variables
	String newVariableName = dialog.getVariableName();
	IPath newVariableValue = new Path(dialog.getVariableValue());
	tempPathVariables.put(newVariableName, newVariableValue);

	// the UI must be updated
	updateWidgetState(newVariableName);
	}
	/**
	* Creates the widget group.
	* Callers must call <code>dispose</code> when the group is no
	* longer needed.
	*
	* @param parent the widget parent
	* @return container of the widgets
	*/
	public Control createContents(Composite parent) {
	Font font = parent.getFont();

	if (imageUnkown == null ) {
	ImageDescriptor descriptor = WorkbenchImages.getImageDescriptorFromPluginID(
	PlatformUI.PLUGIN_ID,
	"icons/full/obj16/question.gif"); //$NON-NLS-1$
	imageUnkown = descriptor.createImage();
	}
	initializeDialogUnits(parent);
	shell = parent.getShell();

	// define container & its layout
	Composite pageComponent = new Composite(parent, SWT.NULL);
	GridLayout layout = new GridLayout();
	layout.numColumns = 2;
	layout.marginWidth = 0;
	layout.marginHeight = 0;
	pageComponent.setLayout(layout);
	GridData data = new GridData(GridData.FILL_BOTH);
	data.widthHint = SIZING_SELECTION_PANE_WIDTH;
	pageComponent.setLayoutData(data);
	pageComponent.setFont(font);

	// layout the table & its buttons
	Label variableLabel = new Label(pageComponent, SWT.LEFT);
	variableLabel.setText(WorkbenchMessages.getString("PathVariablesBlock.variablesLabel")); //$NON-NLS-1$
	data = new GridData();
	data.horizontalAlignment = GridData.FILL;
	data.horizontalSpan = 2;
	variableLabel.setLayoutData(data);
	variableLabel.setFont(font);

	int tableStyle = SWT.BORDER \| SWT.FULL_SELECTION;
	if (multiSelect) {
	tableStyle \|= SWT.MULTI;
	}
	variableTable = new Table(pageComponent, tableStyle);
	variableTable.addSelectionListener(new SelectionAdapter() {
	public void widgetSelected(SelectionEvent e) {
	updateEnabledState();
	}
	});
	data = new GridData(GridData.FILL_BOTH);
	data.heightHint = variableTable.getItemHeight() * 7;
	variableTable.setLayoutData(data);
	variableTable.setFont(font);

	createButtonGroup(pageComponent);
	// populate table with current internal state and set buttons' initial state
	updateWidgetState(null);

	return pageComponent;
	}
	/**
	* Disposes the group's resources.
	*/
	public void dispose() {
	if (imageUnkown != null) {
	imageUnkown.dispose();
	imageUnkown = null;
	}
	}
	/**
	* Opens a dialog for editing an existing variable.
	*
	* @see PathVariableDialog
	*/
	private void editSelectedVariable() {
	// retrieves the name and value for the currently selected variable
	TableItem item = variableTable.getItem(variableTable.getSelectionIndex());
	String variableName = (String) item.getData();
	IPath variableValue = (IPath) tempPathVariables.get(variableName);

	// constructs a dialog for editing the variable's current name and value
	PathVariableDialog dialog =
	new PathVariableDialog(
	shell,
	PathVariableDialog.EXISTING_VARIABLE,
	variableType,
	pathVariableManager,
	tempPathVariables.keySet());
	dialog.setVariableName(variableName);
	dialog.setVariableValue(variableValue.toString());

	// opens the dialog - just returns if the user cancels it
	if (dialog.open() == Window.CANCEL)
	return;

	// the name can be changed, so we remove the current variable definition...
	removedVariableNames.add(variableName);
	tempPathVariables.remove(variableName);

	String newVariableName = dialog.getVariableName();
	IPath newVariableValue = new Path(dialog.getVariableValue());

	// and add it again (maybe with a different name)
	tempPathVariables.put(newVariableName, newVariableValue);

	// now we must refresh the UI state
	updateWidgetState(newVariableName);

	}
	/**
	* Returns the names of the selected variables.
	*
	* @return the names of the selected variables. Returns an empty
	* array if the widget group has not been created yet by calling
	* <code>createContents</code>
	*/
	public String[] getSelection() {
	if (variableTable == null) {
	return new String[0];
	}
	TableItem[] items = variableTable.getSelection();
	String[] variableNames = new String[items.length];

	for (int i = 0; i < items.length; i++) {
	variableNames[i] = (String) items[i].getData();
	}
	return variableNames;
	}
	/**
	* Creates the add/edit/remove buttons
	*
	* @param parent the widget parent
	*/
	private void createButtonGroup(Composite parent) {
	Font font = parent.getFont();
	Composite groupComponent = new Composite(parent, SWT.NULL);
	GridLayout groupLayout = new GridLayout();
	groupLayout.marginWidth = 0;
	groupLayout.marginHeight = 0;
	groupComponent.setLayout(groupLayout);
	GridData data = new GridData();
	data.verticalAlignment = GridData.FILL;
	data.horizontalAlignment = GridData.FILL;
	groupComponent.setLayoutData(data);
	groupComponent.setFont(font);

	addButton = new Button(groupComponent, SWT.PUSH);
	addButton.setText(WorkbenchMessages.getString("PathVariablesBlock.addVariableButton")); //$NON-NLS-1$
	addButton.addSelectionListener(new SelectionAdapter() {
	public void widgetSelected(SelectionEvent e) {
	addNewVariable();
	}
	});
	addButton.setFont(font);
	setButtonLayoutData(addButton);

	editButton = new Button(groupComponent, SWT.PUSH);
	editButton.setText(WorkbenchMessages.getString("PathVariablesBlock.editVariableButton")); //$NON-NLS-1$
	editButton.addSelectionListener(new SelectionAdapter() {
	public void widgetSelected(SelectionEvent e) {
	editSelectedVariable();
	}
	});
	editButton.setFont(font);
	setButtonLayoutData(editButton);

	removeButton = new Button(groupComponent, SWT.PUSH);
	removeButton.setText(WorkbenchMessages.getString("PathVariablesBlock.removeVariableButton")); //$NON-NLS-1$
	removeButton.addSelectionListener(new SelectionAdapter() {
	public void widgetSelected(SelectionEvent e) {
	removeSelectedVariables();
	}
	});
	removeButton.setFont(font);
	setButtonLayoutData(removeButton);
	}
	/**
	* Initializes the computation of horizontal and vertical dialog units
	* based on the size of current font.
	* <p>
	* This method must be called before <code>setButtonLayoutData</code>
	* is called.
	* </p>
	*
	* @param control a control from which to obtain the current font
	*/
	protected void initializeDialogUnits(Control control) {
	// Compute and store a font metric
	GC gc = new GC(control);
	gc.setFont(control.getFont());
	fontMetrics = gc.getFontMetrics();
	gc.dispose();
	}
	/**
	* (Re-)Initialize collections used to mantain temporary variable state.
	*/
	private void initTemporaryState() {
	String[] varNames = pathVariableManager.getPathVariableNames();

	tempPathVariables.clear();
	for (int i = 0; i < varNames.length; i++) {
	IPath value = pathVariableManager.getValue(varNames[i]);

	// the value may not exist any more
	if (value != null) {
	boolean isFile = value.toFile().isFile();
	if ((isFile && (variableType & IResource.FILE) != 0) \|\|
	(isFile == false && (variableType & IResource.FOLDER) != 0)) {

	tempPathVariables.put(varNames[i], value);
	}
	}
	}
	removedVariableNames.clear();
	}
	/**
	* Updates button enabled state, depending on the number of currently selected
	* variables in the table.
	*/
	private void updateEnabledState() {
	int itemsSelectedCount = variableTable.getSelectionCount();
	editButton.setEnabled(itemsSelectedCount == 1);
	removeButton.setEnabled(itemsSelectedCount > 0);
	}
	/**
	* Rebuilds table widget state with the current list of variables (reflecting
	* any changes, additions and removals), and selects the item corresponding to
	* the given variable name. If the variable name is <code>null</code>, the
	* first item (if any) will be selected.
	*
	* @param selectedVarName the name for the variable to be selected (may be
	* <code>null</code>)
	* @see IPathVariableManager#getPathVariableNames()
	* @see IPathVariableManager#getValue(String)
	*/
	private void updateVariableTable(String selectedVarName) {
	variableTable.removeAll();
	int selectedVarIndex = 0;
	for (Iterator varNames = tempPathVariables.keySet().iterator(); varNames.hasNext();) {
	TableItem item = new TableItem(variableTable, SWT.NONE);
	String varName = (String) varNames.next();
	IPath value = (IPath) tempPathVariables.get(varName);
	File file = value.toFile();

	item.setText(varName + " - " + value.toString()); //$NON-NLS-1$
	// the corresponding variable name is stored in each table widget item
	item.setData(varName);
	item.setImage(file.exists() ? (file.isFile() ? FILE_IMG : FOLDER_IMG) : imageUnkown);
	if (varName.equals(selectedVarName))
	selectedVarIndex = variableTable.getItemCount() - 1;
	}
	if (variableTable.getItemCount() > selectedVarIndex)
	variableTable.setSelection(selectedVarIndex);
	}
	/**
	* Commits the temporary state to the path variable manager in response to user
	* confirmation.
	*
	* @see IPathVariableManager#setValue(String, IPath)
	*/
	public boolean performOk() {
	try {
	// first process removed variables
	for (Iterator removed = removedVariableNames.iterator(); removed.hasNext();) {
	String removedVariableName = (String) removed.next();
	// only removes variables that have not been added again
	if (!tempPathVariables.containsKey(removedVariableName))
	pathVariableManager.setValue(removedVariableName, null);
	}

	// then process the current collection of variables, adding/updating them
	for (Iterator current = tempPathVariables.entrySet().iterator(); current.hasNext();) {
	Map.Entry entry = (Map.Entry) current.next();
	String variableName = (String) entry.getKey();
	IPath variableValue = (IPath) entry.getValue();
	pathVariableManager.setValue(variableName, variableValue);
	}
	// re-initialize temporary state
	initTemporaryState();

	// performOk accepted
	return true;
	} catch (CoreException ce) {
	ErrorDialog.openError(shell, null, null, ce.getStatus());
	}
	return false;
	}
	/**
	* Removes the currently selected variables.
	*/
	private void removeSelectedVariables() {
	// remove each selected element
	int[] selectedIndices = variableTable.getSelectionIndices();
	for (int i = 0; i < selectedIndices.length; i++) {
	TableItem selectedItem = variableTable.getItem(selectedIndices[i]);
	String varName = (String) selectedItem.getData();
	removedVariableNames.add(varName);
	tempPathVariables.remove(varName);
	}
	updateWidgetState(null);
	}
	/**
	* Sets the <code>GridData</code> on the specified button to
	* be one that is spaced for the current dialog page units. The
	* method <code>initializeDialogUnits</code> must be called once
	* before calling this method for the first time.
	*
	* @param button the button to set the <code>GridData</code>
	* @return the <code>GridData</code> set on the specified button
	*/
	private GridData setButtonLayoutData(Button button) {
	GridData data = new GridData(GridData.HORIZONTAL_ALIGN_FILL);
	data.heightHint = Dialog.convertVerticalDLUsToPixels(fontMetrics, IDialogConstants.BUTTON_HEIGHT);
	int widthHint = Dialog.convertHorizontalDLUsToPixels(fontMetrics, IDialogConstants.BUTTON_WIDTH);
	data.widthHint = Math.max(widthHint, button.computeSize(SWT.DEFAULT, SWT.DEFAULT, true).x);
	button.setLayoutData(data);
	return data;
	}
	/**
	* Updates the widget's current state: refreshes the table with the current
	* defined variables, selects the item corresponding to the given variable
	* (selects the first item if <code>null</code> is provided) and updates
	* the enabled state for the Add/Remove/Edit buttons.
	*
	* @param selectedVarName the name of the variable to be selected (may be null)
	*/
	private void updateWidgetState(String selectedVarName) {
	updateVariableTable(selectedVarName);
	updateEnabledState();
	}
	}