Registered ContextualBalloon view element in ui focus tracker.

src/panel/balloon/contextualballoon.js

@@ -49,6 +49,9 @@ export default class ContextualBalloon extends Plugin {
 		 */
 		this._stack = new Map();
 
+		// Editor should be focused when contextual balloon is focused.
+		this.editor.ui.focusTracker.add( this.view.element );
+
 		// Add balloon panel view to editor `body` collection and wait until view will be ready.
 		return this.editor.ui.view.body.add( this.view );
 	}

tests/panel/balloon/contextualballoon.js

@@ -10,7 +10,7 @@ import View from '../../../src/view';
 import CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';
 import Plugin from '@ckeditor/ckeditor5-core/src/plugin';
 
-/* global document, setTimeout */
+/* global document, Event, setTimeout */
 
 describe( 'ContextualBalloon', () => {
 	let editor, editorElement, balloon, viewA, viewB;
@@ -66,6 +66,19 @@ describe( 'ContextualBalloon', () => {
 		it( 'should add balloon panel view to editor `body` collection', () => {
 			expect( editor.ui.view.body.getIndex( balloon.view ) ).to.above( -1 );
 		} );
+
+		it( 'should register balloon panel element in editor.ui#focusTracker', () => {
+			editor.ui.focusTracker.isfocused = false;
+
+			balloon.add( {
+				view: viewB,
+				position: { target: 'fake' }
+			} );
+
+			balloon.view.element.dispatchEvent( new Event( 'focus' ) );
+
+			expect( editor.ui.focusTracker.isFocused ).to.true;
+		} );
 	} );
 
 	describe( 'hasView()', () => {