7 files changed, 458 insertions, 255 deletions

diff --git a/java/org/gnu/emacs/EmacsActivity.java b/java/org/gnu/emacs/EmacsActivity.java
index e380b7bfc2a..a939641a752 100644
--- a/java/org/gnu/emacs/EmacsActivity.java
+++ b/java/org/gnu/emacs/EmacsActivity.java
@@ -50,7 +50,7 @@ import android.view.WindowInsetsController;
 import android.widget.FrameLayout;
 
 public class EmacsActivity extends Activity
-  implements EmacsWindowAttachmentManager.WindowConsumer,
+  implements EmacsWindowManager.WindowConsumer,
   ViewTreeObserver.OnGlobalLayoutListener
 {
   public static final String TAG = "EmacsActivity";
@@ -218,7 +218,7 @@ public class EmacsActivity extends Activity
   }
 
   @Override
-  public final void
+  public void
   onCreate (Bundle savedInstanceState)
   {
     FrameLayout.LayoutParams params;
@@ -249,7 +249,7 @@ public class EmacsActivity extends Activity
     EmacsService.startEmacsService (this);
 
     /* Add this activity to the list of available activities.  */
-    EmacsWindowAttachmentManager.MANAGER.registerWindowConsumer (this);
+    EmacsWindowManager.MANAGER.registerWindowConsumer (this);
 
     /* Start observing global layout changes between Jelly Bean and Q.
        This is required to restore the fullscreen state whenever the
@@ -326,16 +326,16 @@ public class EmacsActivity extends Activity
   public final void
   onDestroy ()
   {
-    EmacsWindowAttachmentManager manager;
-    boolean isMultitask;
+    EmacsWindowManager manager;
+    boolean isMultitask, reallyFinishing;
 
-    manager = EmacsWindowAttachmentManager.MANAGER;
+    manager = EmacsWindowManager.MANAGER;
 
     /* The activity will die shortly hereafter.  If there is a window
        attached, close it now.  */
     isMultitask = this instanceof EmacsMultitaskActivity;
-    manager.removeWindowConsumer (this, (isMultitask
-                                         || isReallyFinishing ()));
+    reallyFinishing = isReallyFinishing ();
+    manager.removeWindowConsumer (this, isMultitask || reallyFinishing);
     focusedActivities.remove (this);
     invalidateFocus (2);
 
@@ -383,7 +383,7 @@ public class EmacsActivity extends Activity
   {
     isPaused = true;
 
-    EmacsWindowAttachmentManager.MANAGER.noticeIconified (this);
+    EmacsWindowManager.MANAGER.noticeIconified (this);
     super.onPause ();
   }
 
@@ -394,7 +394,7 @@ public class EmacsActivity extends Activity
     isPaused = false;
     timeOfLastInteraction = 0;
 
-    EmacsWindowAttachmentManager.MANAGER.noticeDeiconified (this);
+    EmacsWindowManager.MANAGER.noticeDeiconified (this);
     super.onResume ();
   }
 
@@ -538,6 +538,14 @@ public class EmacsActivity extends Activity
 
     EmacsNative.sendNotificationAction (tag, action);
   }
+
+  @Override
+  public long
+  getAttachmentToken ()
+  {
+    return -1; /* This is overridden by EmacsMultitaskActivity.  */
+  }
+
 
 
   @Override
diff --git a/java/org/gnu/emacs/EmacsMultitaskActivity.java b/java/org/gnu/emacs/EmacsMultitaskActivity.java
index 7229e34496e..10963ecfd3f 100644
--- a/java/org/gnu/emacs/EmacsMultitaskActivity.java
+++ b/java/org/gnu/emacs/EmacsMultitaskActivity.java
@@ -19,11 +19,39 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 
 package org.gnu.emacs;
 
-/* This class only exists because EmacsActivity is already defined as
-   an activity, and the system wants a new class in order to define a
-   new activity.  */
+import android.content.Intent;
+
+import android.os.Bundle;
+
+/* In large measure, this class only exists because EmacsActivity is
+   already defined as an activity, and the system requires that every
+   new activity be defined by a new class.  */
 
 public final class EmacsMultitaskActivity extends EmacsActivity
 {
-
-}
+  /* Token provided by the creator.  */
+  private long activityToken;
+
+  @Override
+  public final void
+  onCreate (Bundle savedInstanceState)
+  {
+    Intent intent;
+    String token;
+
+    intent = getIntent ();
+    token  = EmacsWindowManager.ACTIVITY_TOKEN;
+
+    if (intent != null)
+      activityToken = intent.getLongExtra (token, -2);
+
+    super.onCreate (savedInstanceState);
+  }
+
+  @Override
+  public final long
+  getAttachmentToken ()
+  {
+    return activityToken;
+  }
+};
diff --git a/java/org/gnu/emacs/EmacsService.java b/java/org/gnu/emacs/EmacsService.java
index 446cd26a3dd..171b427b05b 100644
--- a/java/org/gnu/emacs/EmacsService.java
+++ b/java/org/gnu/emacs/EmacsService.java
@@ -494,7 +494,7 @@ public final class EmacsService extends Service
 
     if (window == null)
       /* Just return all the windows without a parent.  */
-      windowList = EmacsWindowAttachmentManager.MANAGER.copyWindows ();
+      windowList = EmacsWindowManager.MANAGER.copyWindows ();
     else
       windowList = window.children;
 
diff --git a/java/org/gnu/emacs/EmacsView.java b/java/org/gnu/emacs/EmacsView.java
index 109208b2518..37aeded9938 100644
--- a/java/org/gnu/emacs/EmacsView.java
+++ b/java/org/gnu/emacs/EmacsView.java
@@ -511,6 +511,8 @@ public final class EmacsView extends ViewGroup
         && !EmacsNative.shouldForwardMultimediaButtons ())
       return false;
 
+    Log.d (TAG, "onKeyDown: " + event.toString ());
+
     window.onKeyDown (keyCode, event);
     return true;
   }
@@ -708,12 +710,12 @@ public final class EmacsView extends ViewGroup
     contextMenu = null;
     popupActive = false;
 
-    /* It is not possible to know with 100% certainty which activity
-       is currently displaying the context menu.  Loop through each
-       activity and call `closeContextMenu' instead.  */
+    /* It is not possible to know with 100% certainty which activity is
+       currently displaying the context menu.  Loop over each activity
+       and call `closeContextMenu' instead.  */
 
-    for (EmacsWindowAttachmentManager.WindowConsumer consumer
-           : EmacsWindowAttachmentManager.MANAGER.consumers)
+    for (EmacsWindowManager.WindowConsumer consumer
+           : EmacsWindowManager.MANAGER.consumers)
       {
         if (consumer instanceof EmacsActivity)
           ((EmacsActivity) consumer).closeContextMenu ();
diff --git a/java/org/gnu/emacs/EmacsWindow.java b/java/org/gnu/emacs/EmacsWindow.java
index 2baede1d2d0..9b444c3f144 100644
--- a/java/org/gnu/emacs/EmacsWindow.java
+++ b/java/org/gnu/emacs/EmacsWindow.java
@@ -112,7 +112,7 @@ public final class EmacsWindow extends EmacsHandleObject
   private SparseArray<Coordinate> pointerMap;
 
   /* The window consumer currently attached, if it exists.  */
-  private EmacsWindowAttachmentManager.WindowConsumer attached;
+  private EmacsWindowManager.WindowConsumer attached;
 
   /* The window background scratch GC.  foreground is always the
      window background.  */
@@ -159,6 +159,16 @@ public final class EmacsWindow extends EmacsHandleObject
      values are -1 if no drag and drop operation is under way.  */
   private int dndXPosition, dndYPosition;
 
+  /* Identifier binding this window to the activity created for it, or
+     -1 if the window should be attached to system-created activities
+     (i.e. the activity launched by the system at startup).  Value is
+     meaningless under API level 29 and earlier.  */
+  public long attachmentToken;
+
+  /* Whether this window should be preserved during window pruning,
+     and whether this window has previously been attached to a task.  */
+  public boolean preserve, previouslyAttached;
+
   public
   EmacsWindow (short handle, final EmacsWindow parent, int x, int y,
                int width, int height, boolean overrideRedirect)
@@ -255,12 +265,12 @@ public final class EmacsWindow extends EmacsHandleObject
         run ()
         {
           ViewManager parent;
-          EmacsWindowAttachmentManager manager;
+          EmacsWindowManager manager;
 
           if (EmacsActivity.focusedWindow == EmacsWindow.this)
             EmacsActivity.focusedWindow = null;
 
-          manager = EmacsWindowAttachmentManager.MANAGER;
+          manager = EmacsWindowManager.MANAGER;
           view.setVisibility (View.GONE);
 
           /* If the window manager is set, use that instead.  */
@@ -281,12 +291,12 @@ public final class EmacsWindow extends EmacsHandleObject
   }
 
   public void
-  setConsumer (EmacsWindowAttachmentManager.WindowConsumer consumer)
+  setConsumer (EmacsWindowManager.WindowConsumer consumer)
   {
     attached = consumer;
   }
 
-  public EmacsWindowAttachmentManager.WindowConsumer
+  public EmacsWindowManager.WindowConsumer
   getAttachedConsumer ()
   {
     return attached;
@@ -420,7 +430,7 @@ public final class EmacsWindow extends EmacsHandleObject
             public void
             run ()
             {
-              EmacsWindowAttachmentManager manager;
+              EmacsWindowManager manager;
               WindowManager windowManager;
               Activity ctx;
               Object tem;
@@ -431,7 +441,7 @@ public final class EmacsWindow extends EmacsHandleObject
 
               if (!overrideRedirect)
                 {
-                  manager = EmacsWindowAttachmentManager.MANAGER;
+                  manager = EmacsWindowManager.MANAGER;
 
                   /* If parent is the root window, notice that there are new
                      children available for interested activities to pick
@@ -527,9 +537,9 @@ public final class EmacsWindow extends EmacsHandleObject
         public void
         run ()
         {
-          EmacsWindowAttachmentManager manager;
+          EmacsWindowManager manager;
 
-          manager = EmacsWindowAttachmentManager.MANAGER;
+          manager = EmacsWindowManager.MANAGER;
 
           view.setVisibility (View.GONE);
 
@@ -809,20 +819,13 @@ public final class EmacsWindow extends EmacsHandleObject
     EmacsActivity.invalidateFocus (gainFocus ? 6 : 5);
   }
 
-  /* Notice that the activity has been detached or destroyed.
-
-     ISFINISHING is set if the activity is not the main activity, or
-     if the activity was not destroyed in response to explicit user
-     action.  */
+  /* Notice that the activity (or its task) has been detached or
+     destroyed by explicit user action.  */
 
   public void
-  onActivityDetached (boolean isFinishing)
+  onActivityDetached ()
   {
-    /* Destroy the associated frame when the activity is detached in
-       response to explicit user action.  */
-
-    if (isFinishing)
-      EmacsNative.sendWindowAction (this.handle, 0);
+    EmacsNative.sendWindowAction (this.handle, 0);
   }
 
 
@@ -1312,13 +1315,17 @@ public final class EmacsWindow extends EmacsHandleObject
         public void
         run ()
         {
-          EmacsWindowAttachmentManager manager;
+          EmacsWindowManager manager;
           ViewManager parent;
 
           /* First, detach this window if necessary.  */
-          manager = EmacsWindowAttachmentManager.MANAGER;
+          manager = EmacsWindowManager.MANAGER;
           manager.detachWindow (EmacsWindow.this);
 
+          /* Reset window management state.  */
+          previouslyAttached = false;
+          attachmentToken = false;
+
           /* Also unparent this view.  */
 
           /* If the window manager is set, use that instead.  */
@@ -1858,7 +1865,7 @@ public final class EmacsWindow extends EmacsHandleObject
   public void
   recreateActivity ()
   {
-    final EmacsWindowAttachmentManager.WindowConsumer attached;
+    final EmacsWindowManager.WindowConsumer attached;
 
     attached = this.attached;
 
diff --git a/java/org/gnu/emacs/EmacsWindowAttachmentManager.java b/java/org/gnu/emacs/EmacsWindowAttachmentManager.java
deleted file mode 100644
index aae4e2ee49b..00000000000
--- a/java/org/gnu/emacs/EmacsWindowAttachmentManager.java
+++ /dev/null
@@ -1,211 +0,0 @@
-/* Communication module for Android terminals.  -*- c-file-style: "GNU" -*-
-
-Copyright (C) 2023-2024 Free Software Foundation, Inc.
-
-This file is part of GNU Emacs.
-
-GNU Emacs is free software: you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation, either version 3 of the License, or (at
-your option) any later version.
-
-GNU Emacs is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License
-along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
-
-package org.gnu.emacs;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import android.app.ActivityOptions;
-import android.content.Intent;
-import android.os.Build;
-import android.util.Log;
-
-/* Code to paper over the differences in lifecycles between
-   "activities" and windows.  There are four interfaces to an instance
-   of this class:
-
-     registerWindowConsumer (WindowConsumer)
-     registerWindow (EmacsWindow)
-     removeWindowConsumer (WindowConsumer)
-     removeWindow (EmacsWindow)
-
-   A WindowConsumer is expected to allow an EmacsWindow to be attached
-   to it, and be created or destroyed.
-
-   Every time a window is created, registerWindow checks the list of
-   window consumers.  If a consumer exists and does not currently have
-   a window of its own attached, it gets the new window.  Otherwise,
-   the window attachment manager starts a new consumer.
-
-   Every time a consumer is registered, registerWindowConsumer checks
-   the list of available windows.  If a window exists and is not
-   currently attached to a consumer, then the consumer gets it.
-
-   Finally, every time a window is removed, the consumer is
-   destroyed.  */
-
-public final class EmacsWindowAttachmentManager
-{
-  private final static String TAG = "EmacsWindowAttachmentManager";
-
-  /* The single window attachment manager ``object''.  */
-  public static final EmacsWindowAttachmentManager MANAGER;
-
-  static
-  {
-    MANAGER = new EmacsWindowAttachmentManager ();
-  };
-
-  public interface WindowConsumer
-  {
-    public void attachWindow (EmacsWindow window);
-    public EmacsWindow getAttachedWindow ();
-    public void detachWindow ();
-    public void destroy ();
-  };
-
-  /* List of currently attached window consumers.  */
-  public List<WindowConsumer> consumers;
-
-  /* List of currently attached windows.  */
-  public List<EmacsWindow> windows;
-
-  public
-  EmacsWindowAttachmentManager ()
-  {
-    consumers = new ArrayList<WindowConsumer> ();
-    windows = new ArrayList<EmacsWindow> ();
-  }
-
-  public void
-  registerWindowConsumer (WindowConsumer consumer)
-  {
-    consumers.add (consumer);
-
-    for (EmacsWindow window : windows)
-      {
-        if (window.getAttachedConsumer () == null)
-          {
-            consumer.attachWindow (window);
-            return;
-          }
-      }
-
-    EmacsNative.sendWindowAction ((short) 0, 0);
-  }
-
-  public synchronized void
-  registerWindow (EmacsWindow window)
-  {
-    Intent intent;
-    ActivityOptions options;
-
-    if (windows.contains (window))
-      /* The window is already registered.  */
-      return;
-
-    windows.add (window);
-
-    for (WindowConsumer consumer : consumers)
-      {
-        if (consumer.getAttachedWindow () == null)
-          {
-            consumer.attachWindow (window);
-            return;
-          }
-      }
-
-    intent = new Intent (EmacsService.SERVICE,
-                         EmacsMultitaskActivity.class);
-
-    intent.addFlags (Intent.FLAG_ACTIVITY_NEW_TASK
-                     | Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
-
-    /* Intent.FLAG_ACTIVITY_NEW_DOCUMENT is lamentably unavailable on
-       older systems than Lolipop.  */
-    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
-      intent.addFlags (Intent.FLAG_ACTIVITY_NEW_DOCUMENT);
-
-    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N)
-      EmacsService.SERVICE.startActivity (intent);
-    else
-      {
-        /* Specify the desired window size.  */
-        options = ActivityOptions.makeBasic ();
-        options.setLaunchBounds (window.getGeometry ());
-        EmacsService.SERVICE.startActivity (intent,
-                                            options.toBundle ());
-      }
-  }
-
-  public void
-  removeWindowConsumer (WindowConsumer consumer, boolean isFinishing)
-  {
-    EmacsWindow window;
-
-    window = consumer.getAttachedWindow ();
-
-    if (window != null)
-      {
-        consumer.detachWindow ();
-        window.onActivityDetached (isFinishing);
-      }
-
-    consumers.remove (consumer);
-  }
-
-  public synchronized void
-  detachWindow (EmacsWindow window)
-  {
-    WindowConsumer consumer;
-
-    if (window.getAttachedConsumer () != null)
-      {
-        consumer = window.getAttachedConsumer ();
-
-        consumers.remove (consumer);
-        consumer.destroy ();
-      }
-
-    windows.remove (window);
-  }
-
-  public void
-  noticeIconified (WindowConsumer consumer)
-  {
-    EmacsWindow window;
-
-    /* If a window is attached, send the appropriate iconification
-       events.  */
-    window = consumer.getAttachedWindow ();
-
-    if (window != null)
-      window.noticeIconified ();
-  }
-
-  public void
-  noticeDeiconified (WindowConsumer consumer)
-  {
-    EmacsWindow window;
-
-    /* If a window is attached, send the appropriate iconification
-       events.  */
-    window = consumer.getAttachedWindow ();
-
-    if (window != null)
-      window.noticeDeiconified ();
-  }
-
-  public synchronized List<EmacsWindow>
-  copyWindows ()
-  {
-    return new ArrayList<EmacsWindow> (windows);
-  }
-};
diff --git a/java/org/gnu/emacs/EmacsWindowManager.java b/java/org/gnu/emacs/EmacsWindowManager.java
new file mode 100644
index 00000000000..fb4ef6344b2
--- /dev/null
+++ b/java/org/gnu/emacs/EmacsWindowManager.java
@@ -0,0 +1,369 @@
+/* Communication module for Android terminals.  -*- c-file-style: "GNU" -*-
+
+Copyright (C) 2023-2024 Free Software Foundation, Inc.
+
+This file is part of GNU Emacs.
+
+GNU Emacs is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or (at
+your option) any later version.
+
+GNU Emacs is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
+
+package org.gnu.emacs;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import android.app.ActivityManager.AppTask;
+import android.app.ActivityManager;
+import android.app.ActivityOptions;
+import android.app.TaskInfo;
+
+import android.content.Context;
+import android.content.Intent;
+
+import android.os.Build;
+
+import android.util.Log;
+
+/* Code to paper over the differences in lifecycles between
+   "activities" and windows.
+
+   Four of the five interfaces to be implemented by an instance of this
+   class are relevant on all versions of Android:
+
+     registerWindowConsumer (WindowConsumer)
+     registerWindow (EmacsWindow)
+     removeWindowConsumer (WindowConsumer)
+     removeWindow (EmacsWindow)
+
+   A WindowConsumer is expected to allow an EmacsWindow to be attached
+   to it, and be created or destroyed.
+
+   Whenever a window is created, registerWindow examines the list of
+   window consumers.  If a consumer exists and does not currently have a
+   window of its own attached, it gets the new window, while otherwise,
+   the window attachment manager starts a new consumer.  Whenever a
+   consumer is registered, registerWindowConsumer checks the list of
+   available windows.  If a window exists and is not currently attached
+   to a consumer, then the consumer gets it.  Finally, every time a
+   window is removed, the consumer is destroyed.
+
+     getAttachmentToken ()
+
+   should return a token uniquely identifying a consumer, which, on API
+   29 and up, enables attributing the tasks of activities to the windows
+   for which they were created, and with that, consistent interaction
+   between user-visible window state and their underlying frames.  */
+
+public final class EmacsWindowManager
+{
+  private static final String TAG = "EmacsWindowManager";
+  public  final static String ACTIVITY_TOKEN = "emacs:activity_token";
+
+  /* The single window attachment manager ``object''.  */
+  public static final EmacsWindowManager MANAGER;
+
+  /* Monotonically increasing counter from which multitasking activity
+     tokens are produced.  */
+  private static long nextActivityToken;
+
+  /* The ActivityManager.  */
+  private ActivityManager activityManager;
+
+  static
+  {
+    MANAGER = new EmacsWindowManager ();
+  };
+
+  public interface WindowConsumer
+  {
+    public void attachWindow (EmacsWindow window);
+    public EmacsWindow getAttachedWindow ();
+    public void detachWindow ();
+    public void destroy ();
+    public long getAttachmentToken ();
+  };
+
+  /* List of currently attached window consumers.  */
+  public List<WindowConsumer> consumers;
+
+  /* List of currently attached windows.  */
+  public List<EmacsWindow> windows;
+
+  public
+  EmacsWindowManager ()
+  {
+    consumers = new ArrayList<WindowConsumer> ();
+    windows = new ArrayList<EmacsWindow> ();
+  }
+
+
+
+
+  /* Return whether the provided WINDOW should be attached to the window
+     consumer CONSUMER.  */
+
+  public static boolean
+  isWindowEligible (WindowConsumer consumer, EmacsWindow window)
+  {
+    return (/* The window has yet to be bound.  */
+            window.attachmentToken == 0
+            /* Or has already been bound to CONSUMER.  */
+            || (window.attachmentToken
+                == consumer.getAttachmentToken ()));
+  }
+
+
+
+  public synchronized void
+  registerWindowConsumer (WindowConsumer consumer)
+  {
+    consumers.add (consumer);
+    pruneWindows ();
+
+    for (EmacsWindow window : windows)
+      {
+        if (window.getAttachedConsumer () == null
+            /* Don't attach this window to CONSUMER if incompatible.  */
+            && isWindowEligible (consumer, window))
+          {
+            /* Permantly bind this window to the consumer.  */
+            window.attachmentToken = consumer.getAttachmentToken ();
+            window.previouslyAttached = true;
+            consumer.attachWindow (window);
+            return;
+          }
+      }
+
+    EmacsNative.sendWindowAction ((short) 0, 0);
+  }
+
+  public synchronized void
+  registerWindow (EmacsWindow window)
+  {
+    Intent intent;
+    ActivityOptions options;
+    long token;
+
+    if (windows.contains (window))
+      /* The window is already registered.  */
+      return;
+
+    windows.add (window);
+
+    for (WindowConsumer consumer : consumers)
+      {
+        if (consumer.getAttachedWindow () == null
+            && isWindowEligible (consumer, window))
+          {
+            /* Permantly bind this window to the consumer.  */
+            window.attachmentToken = consumer.getAttachmentToken ();
+            window.previouslyAttached = true;
+            consumer.attachWindow (window);
+            return;
+          }
+      }
+
+    intent = new Intent (EmacsService.SERVICE,
+                         EmacsMultitaskActivity.class);
+
+    intent.addFlags (Intent.FLAG_ACTIVITY_NEW_TASK
+                     | Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
+
+    /* Intent.FLAG_ACTIVITY_NEW_DOCUMENT is lamentably unavailable on
+       older systems than Lolipop.  */
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
+      intent.addFlags (Intent.FLAG_ACTIVITY_NEW_DOCUMENT);
+
+    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N)
+      EmacsService.SERVICE.startActivity (intent);
+    else
+      {
+        /* Specify the desired window size.  */
+        options = ActivityOptions.makeBasic ();
+        options.setLaunchBounds (window.getGeometry ());
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q)
+          /* Bind this window to the activity in advance, i.e., before
+             its creation, so that its ID will be recorded in the
+             RecentTasks list.  */
+          token = ++nextActivityToken;
+        else
+          /* APIs required for linking activities to windows are not
+             available in earlier Android versions.  */
+          token = -2;
+
+        window.attachmentToken = token;
+        intent.putExtra (ACTIVITY_TOKEN, token);
+        EmacsService.SERVICE.startActivity (intent, options.toBundle ());
+      }
+
+    pruneWindows ();
+  }
+
+  public synchronized void
+  removeWindowConsumer (WindowConsumer consumer, boolean isFinishing)
+  {
+    EmacsWindow window;
+
+    window = consumer.getAttachedWindow ();
+
+    if (window != null)
+      {
+        consumer.detachWindow ();
+
+        /* Though pruneWindows will likely remove the same windows, call
+           onActivityDetached anyway if isFinishing is set, as in
+           obscure circumstances pruneWindows will not remove frames
+           bound to the system-started task.  */
+        if (isFinishing)
+          window.onActivityDetached ();
+      }
+
+    pruneWindows ();
+    consumers.remove (consumer);
+  }
+
+  public synchronized void
+  detachWindow (EmacsWindow window)
+  {
+    WindowConsumer consumer;
+
+    if (window.getAttachedConsumer () != null)
+      {
+        consumer = window.getAttachedConsumer ();
+
+        consumers.remove (consumer);
+        consumer.destroy ();
+      }
+
+    pruneWindows ();
+    windows.remove (window);
+  }
+
+  public void
+  noticeIconified (WindowConsumer consumer)
+  {
+    EmacsWindow window;
+
+    /* If a window is attached, send the appropriate iconification
+       events.  */
+    window = consumer.getAttachedWindow ();
+
+    if (window != null)
+      window.noticeIconified ();
+  }
+
+  public void
+  noticeDeiconified (WindowConsumer consumer)
+  {
+    EmacsWindow window;
+
+    /* If a window is attached, send the appropriate iconification
+       events.  */
+    window = consumer.getAttachedWindow ();
+
+    if (window != null)
+      window.noticeDeiconified ();
+  }
+
+  public synchronized List<EmacsWindow>
+  copyWindows ()
+  {
+    return new ArrayList<EmacsWindow> (windows);
+  }
+
+
+
+  /* Return the activity token specified in the intent giving rise to
+     TASK, or 0 if absent.  */
+
+  private static long
+  getTaskToken (AppTask task)
+  {
+    TaskInfo info;
+
+    info = (TaskInfo) task.getTaskInfo ();
+    return (info.baseIntent != null
+            ? info.baseIntent.getLongExtra (ACTIVITY_TOKEN,
+                                            -1l)
+            : 0);
+  }
+
+  /* Iterate over each of Emacs's tasks and remove remaining registered
+     windows whose tasks no longer exist.  This function should be
+     called upon any event that could plausibly indicate changes in the
+     task list or as to window management.  */
+
+  private synchronized void
+  pruneWindows ()
+  {
+    Object object;
+    List<AppTask> appTasks;
+    long taskToken;
+    boolean set;
+
+    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q
+        || EmacsService.SERVICE == null)
+      return;
+
+    if (activityManager == null)
+      {
+        object
+          = EmacsService.SERVICE.getSystemService (Context.ACTIVITY_SERVICE);
+        activityManager = (ActivityManager) object;
+      }
+
+    appTasks = activityManager.getAppTasks ();
+
+    /* Clear the preserve flag on all toplevel windows.  */
+
+    for (EmacsWindow window : windows)
+      window.preserve = false;
+
+    for (AppTask task : appTasks)
+      {
+        taskToken = getTaskToken (task);
+        set = false;
+
+        if (taskToken == 0)
+          continue;
+
+        /* Search for a window with this token.  */
+        for (EmacsWindow window : windows)
+          {
+            if (window.attachmentToken == taskToken)
+              {
+                window.preserve = true;
+                set = true;
+              }
+          }
+
+        if (!set)
+          task.finishAndRemoveTask ();
+      }
+
+    /* Now remove toplevel windows without activity tasks.  */
+
+    for (EmacsWindow window : windows)
+      {
+        if (window.preserve
+            /* This is not the initial window.  */
+            || (window.attachmentToken < 1)
+            /* Nor has it never been attached.  */
+            || !window.previouslyAttached)
+          continue;
+
+        window.onActivityDetached ();
+      }
+  }
+};