Bug 87111 [Dialogs] Feature: add general-purpose page change notification for dialogs
New dynamic help pane attaches itself to all the dialogs that JFace provides. Some of these dialogs manage multiple pages but dynamic help has no way of registering for page change notification. Examples of dialogs that exhibit this behaviour are WizardDialog, PreferenceDialog, LaunchConfigurationDialog (in Debug), PropertiesDialog etc. Attached is the code for the following proposed enhancement: 1) A new interface 'IBaseDialogPage' that interfaces like IDialogPage and ILaunchConfigurationTab can extend 2) A class PageChangedEvent for page change notification 3) A new interface 'IPageChangeProvider' 4) A new interface 'IPageChangedListener' In the attached patch, WizardDialog and PreferenceDialog implement IPageChangeProvider and notify page changed listeners whenever current page changes. This allows dynamic help to update its content and show the relevant help for the currently selected page. Since IBaseDialogPage is now a base interface for IDialogPage, two methods (getTitle() and getControl()) are moved up from IDialogPage. This is consistent with ILaunchConfigurationTab and does not clash with any existing method.
bundles/org.eclipse.jface/src/org/eclipse/jface/wizard/WizardDialog.java
* <p>
 * The standard layout is roughly as follows: 
 * it has an area at the top containing both the
 * wizard's title, description, and image; the actual wizard page
 * appears in the middle; below that is a progress indicator
 * (which is made visible if needed); and at the bottom
 * of the page is message line and a button bar containing 
 * Help, Next, Back, Finish, and Cancel buttons (or some subset).
 * </p>
 * <p>
 * Clients may subclass <code>WizardDialog</code>, although this
 * is rarely required.
 * </p>
 */
public class WizardDialog extends TitleAreaDialog implements IWizardContainer2 {
    /**
     * Image registry key for error message image (value <code>"dialog_title_error_image"</code>).
     */
    public static final String WIZ_IMG_ERROR = "dialog_title_error_image"; 
    
    private IWizard wizard;
    
    private ArrayList createdWizards = new ArrayList();
    
    private ArrayList nestedWizards = new ArrayList();
    
    private IWizardPage currentPage = null;
    	
    private long activeRunningOperations = 0;