Fix sticky cursor resulting in reverse typing if the editable is not the activeElement in the document.

packages/ckeditor5-engine/src/view/observer/inputobserver.ts

@@ -35,6 +35,13 @@ export default class InputObserver extends DomEventObserver<'beforeinput'> {
 		// @if CK_DEBUG_TYPING // 	);
 		// @if CK_DEBUG_TYPING // }
 
+		// Handles reverse typing cases where the current document is not seen as the
+		// DOM `activeElement`, but the editable is somehow still in focus.
+		// In other words, the editable visually appears to be in focus, but it is not.
+		if ( !this.view.document.isFocused ) {
+			// The current target is assumed to be the editable
+			domEvent.currentTarget?.dispatchEvent( new FocusEvent( 'focus' ) );
+		}
 		const domTargetRanges = domEvent.getTargetRanges();
 		const view = this.view;
 		const viewDocument = view.document;

packages/ckeditor5-engine/tests/view/observer/inputobserver.js

@@ -59,6 +59,34 @@ describe( 'InputObserver', () => {
 		sinon.assert.calledOnce( beforeInputSpy );
 	} );
 
+	it( 'should not dispatch focus event if the document has focus', () => {
+		viewDocument.isFocused = true;
+
+		const mockDispatchEvent = sinon.spy();
+		fireMockNativeBeforeInput( {
+			inputType: 'foo',
+			currentTarget: {
+				dispatchEvent: mockDispatchEvent
+			}
+		} );
+
+		expect( mockDispatchEvent.callCount ).to.equal( 0 );
+	} );
+
+	it( 'should dispatch focus event if the document does not have focus', () => {
+		viewDocument.isFocused = false;
+
+		const mockDispatchEvent = sinon.spy();
+		fireMockNativeBeforeInput( {
+			inputType: 'foo',
+			currentTarget: {
+				dispatchEvent: mockDispatchEvent
+			}
+		} );
+
+		expect( mockDispatchEvent.callCount ).to.equal( 1 );
+	} );
+
 	describe( 'event data', () => {
 		it( 'should contain #eventType', () => {
 			fireMockNativeBeforeInput( {