diff --git a/core/java/android/view/inputmethod/InputConnection.java b/core/java/android/view/inputmethod/InputConnection.java
index 5f036a3488083..ccca031aad3f0 100644
--- a/core/java/android/view/inputmethod/InputConnection.java
+++ b/core/java/android/view/inputmethod/InputConnection.java
@@ -843,9 +843,14 @@ public interface InputConnection {
     /**
      * Called back when the connected IME switches between fullscreen and normal modes.
      *
-     * <p>Note: On {@link android.os.Build.VERSION_CODES#O} and later devices, input methods are no
-     * longer allowed to directly call this method at any time. To signal this event in the target
-     * application, input methods should always call
+     * <p><p><strong>Editor authors:</strong> There is a bug on
+     * {@link android.os.Build.VERSION_CODES#O} and later devices that this method is called back
+     * on the main thread even when {@link #getHandler()} is overridden.  This bug is fixed in
+     * {@link android.os.Build.VERSION_CODES#TIRAMISU}.</p>
+     *
+     * <p><p><strong>IME authors:</strong> On {@link android.os.Build.VERSION_CODES#O} and later
+     * devices, input methods are no longer allowed to directly call this method at any time.
+     * To signal this event in the target application, input methods should always call
      * {@link InputMethodService#updateFullscreenMode()} instead. This approach should work on API
      * {@link android.os.Build.VERSION_CODES#N_MR1} and prior devices.</p>
      *
diff --git a/core/java/android/view/inputmethod/InputMethodManager.java b/core/java/android/view/inputmethod/InputMethodManager.java
index c023c6ef04df9..5f659a6afba91 100644
--- a/core/java/android/view/inputmethod/InputMethodManager.java
+++ b/core/java/android/view/inputmethod/InputMethodManager.java
@@ -950,15 +950,15 @@ public final class InputMethodManager {
                 }
                 case MSG_REPORT_FULLSCREEN_MODE: {
                     final boolean fullscreen = msg.arg1 != 0;
-                    InputConnection ic = null;
+                    RemoteInputConnectionImpl ic = null;
                     synchronized (mH) {
                         if (mFullscreenMode != fullscreen && mServedInputConnection != null) {
-                            ic = mServedInputConnection.getInputConnection();
+                            ic = mServedInputConnection;
                             mFullscreenMode = fullscreen;
                         }
                     }
                     if (ic != null) {
-                        ic.reportFullscreenMode(fullscreen);
+                        ic.dispatchReportFullscreenMode(fullscreen);
                     }
                     return;
                 }
diff --git a/core/java/com/android/internal/inputmethod/RemoteInputConnectionImpl.java b/core/java/com/android/internal/inputmethod/RemoteInputConnectionImpl.java
index d1bca85f8425e..6f79fa117c6a1 100644
--- a/core/java/com/android/internal/inputmethod/RemoteInputConnectionImpl.java
+++ b/core/java/com/android/internal/inputmethod/RemoteInputConnectionImpl.java
@@ -169,6 +169,23 @@ public final class RemoteInputConnectionImpl extends IInputContext.Stub {
         }
     }
 
+    /**
+     * Invoke {@link InputConnection#reportFullscreenMode(boolean)} or schedule it on the target
+     * thread associated with {@link InputConnection#getHandler()}.
+     *
+     * @param enabled the parameter to be passed to
+     *                {@link InputConnection#reportFullscreenMode(boolean)}.
+     */
+    public void dispatchReportFullscreenMode(boolean enabled) {
+        dispatch(() -> {
+            final InputConnection ic = getInputConnection();
+            if (ic == null || !isActive()) {
+                return;
+            }
+            ic.reportFullscreenMode(enabled);
+        });
+    }
+
     @Override
     public void getTextAfterCursor(int length, int flags, ICharSequenceResultCallback callback) {
         dispatch(() -> {