Summary
-------

Define a new public API to access platform-specific desktop features such
as interacting with a task bar or dock, or listening for system or
application events.


Goals
-----

In the forthcoming release of JDK 9, internal APIs such as those in the
Mac OS X `com.apple.eawt` package will no longer be
accessible. The goal of this JEP is to provide suitable
replacements for these inaccessible APIs and, also, introduce related
platform-specific features. We plan to implement the new features on
those platforms that have the necessary support. Where feasible, the API
will be designed to be cross-platform so that each feature can be
implemented on as wide a range of platforms as possible. 
`apple.applescript` classes are being removed without providing any replacement.


Non-Goals
---------

We do not intend to provide direct replacements for all of the internal
OS X APIs present in JDK 8. Specifically, we will not provide a
replacement for the `com.apple.concurrent` package. Is it also not a goal
to maintain compatibility with those internal APIs for which we do
provide substitutes.


Description
-----------

This JEP contains two sub-tasks:

### Provide public API to replace the functionality in `com.apple.{eawt,eio}`

The intent of this subtask is to avoid loss of functionality for OS X
developers.  We will provide replacements for the APIs in the
JDK-internal `com.apple.eawt` and `com.apple.eio` packages.

### Provide access to similar features on other platforms

In addition to features specific to OS X, there are similar features that
can be supported on other platforms, including Windows and Linux:

  - Login/logout and screen lock handlers: Provide event listeners on
    system login/logout (or screen lock/unlock) to allow an application
    to start a persistent task or save its state when needed.

  - Task bar/dock interactions

    - Request user attention: Allow an application to request the
      attention of the user, using platform capabilities such as blinking
      the application icon in the taskbar or bouncing the icon in the
      dock.

    - Indicate task progress: Display a progress bar or other indicator
      in the task bar/dock.

    - Action shortcuts: Provide action shortcuts that are accessible by a
      pop-up menu, for example, Windows jump-lists.

Support for these features will be determined by platform capabilities.

### API

We propose to add the public API for these two sub-tasks to the existing
`java.awt.Desktop` class. The target supported platforms are Mac OS X,
Windows, Linux.

Proposed API sketch:

    package java.awt;
    
    public class Desktop {
    
        /* ... */
    
        /**
         * Adds sub-types of {@link AppEventListener} to listen for notifications
         * from the native system.
         *
         * @param listener
         * @see AppForegroundListener
         * @see AppHiddenListener
         * @see AppReOpenedListener
         * @see AppScreenSleepListener
         * @see AppSystemSleepListener
         * @see AppUserSessionListener
         */
    
        public void addAppEventListener(final AppEventListener listener) {}
    
        /**
         * Requests user attention to this application (usually through bouncing the Dock icon).
         * Critical requests will continue to bounce the Dock icon until the app is activated.
         *
         */
        public void requestUserAttention(final boolean critical) {}
    
        /**
         * Attaches the contents of the provided PopupMenu to the application's Dock icon.
         */
        public void setDockMenu(final PopupMenu menu) {}
    
        /**
         * Changes this application's Dock icon to the provided image.
         */
        public void setDockIconImage(final Image image) {}
    
    
        /**
         * Affixes a small system provided badge to this application's Dock icon. Usually a number.
         */
        public void setDockIconBadge(final String badge) {}
    
        /**
         * Displays or hides a progress bar or other indicator in
         * the dock.
         *
         * @see DockProgressState.NORMAL
         * @see DockProgressState.PAUSED
         * @see DockProgressState.ERROR
         *
         * @see #setDockProgressValue
         */
        public void setDockProgressState(int state) {}
    
        /**
         * Sets the progress bar's current value to {@code n}.
         */
        public void setDockProgressValue(int n) {}
    
        /**
         * Tests whether a feature is supported on the current platform.
         */
    
        public boolean isSupportedFeature(Feature f) {}
    
        /* ... */
    }


Testing
-------

Testing will be limited to additional manual tests written to use the new
API. Tests will need to check whether the new features are supported on
platforms where they are expected to be supported, and that they fail
gracefully on platforms with no support.