Fix: Fixed View#render collision when moving focus from a one editable to the other in multi-root editor

src/editableui/editableuiview.js

@@ -122,7 +122,7 @@ export default class EditableUIView extends View {
 		const editingView = this._editingView;
 
 		if ( editingView.isRenderingInProgress ) {
-			editingView.once( 'change:isRenderingInProgress', () => update( this ) );
+			updateAfterRender( this );
 		} else {
 			update( this );
 		}
@@ -135,5 +135,20 @@ export default class EditableUIView extends View {
 				writer.removeClass( view.isFocused ? 'ck-blurred' : 'ck-focused', viewRoot );
 			} );
 		}
+
+		// In a case of a multi-root editor, a callback will be attached more than once (one callback for each root).
+		// While executing one callback the `isRenderingInProgress` observable is changing what causes executing another
+		// callback and render is called inside the already pending render.
+		// We need to be sure that callback is executed only when the value has changed from `true` to `false`.
+		// See https://github.com/ckeditor/ckeditor5/issues/1676.
+		function updateAfterRender( view ) {
+			editingView.once( 'change:isRenderingInProgress', ( evt, name, value ) => {
+				if ( !value ) {
+					update( view );
+				} else {
+					updateAfterRender( view );
+				}
+			} );
+		}
 	}
 }

tests/editableui/editableuiview.js

@@ -80,22 +80,49 @@ describe( 'EditableUIView', () => {
 			} );
 
 			// https://github.com/ckeditor/ckeditor5/issues/1530.
+			// https://github.com/ckeditor/ckeditor5/issues/1676.
 			it( 'should work when update is handled during the rendering phase', () => {
+				const secondEditingViewRoot = new ViewRootEditableElement( 'div' );
+				const secondView = new EditableUIView( locale, editingView );
+				const secondEditableElement = document.createElement( 'div' );
+
+				document.body.appendChild( secondEditableElement );
+
+				secondEditingViewRoot.rootName = 'second';
+				secondEditingViewRoot._document = editingView.document;
+				editingView.document.roots.add( secondEditingViewRoot );
+
+				secondView.name = 'second';
+				secondView.render();
+
+				editingView.attachDomRoot( editableElement, 'main' );
+				editingView.attachDomRoot( secondEditableElement, 'second' );
+
 				view.isFocused = true;
-				editingView.isRenderingInProgress = true;
+				secondView.isFocused = false;
 
-				expect( editingViewRoot.hasClass( 'ck-focused' ) ).to.be.true;
-				expect( editingViewRoot.hasClass( 'ck-blurred' ) ).to.be.false;
+				expect( editingViewRoot.hasClass( 'ck-focused' ), 1 ).to.be.true;
+				expect( editingViewRoot.hasClass( 'ck-blurred' ), 2 ).to.be.false;
+				expect( secondEditingViewRoot.hasClass( 'ck-focused' ), 3 ).to.be.false;
+				expect( secondEditingViewRoot.hasClass( 'ck-blurred' ), 4 ).to.be.true;
 
+				editingView.isRenderingInProgress = true;
 				view.isFocused = false;
+				secondView.isFocused = true;
 
-				expect( editingViewRoot.hasClass( 'ck-focused' ) ).to.be.true;
-				expect( editingViewRoot.hasClass( 'ck-blurred' ) ).to.be.false;
+				expect( editingViewRoot.hasClass( 'ck-focused' ), 5 ).to.be.true;
+				expect( editingViewRoot.hasClass( 'ck-blurred' ), 6 ).to.be.false;
+				expect( secondEditingViewRoot.hasClass( 'ck-focused' ), 7 ).to.be.false;
+				expect( secondEditingViewRoot.hasClass( 'ck-blurred' ), 8 ).to.be.true;
 
 				editingView.isRenderingInProgress = false;
 
-				expect( editingViewRoot.hasClass( 'ck-focused' ) ).to.be.false;
-				expect( editingViewRoot.hasClass( 'ck-blurred' ) ).to.be.true;
+				expect( editingViewRoot.hasClass( 'ck-focused' ), 9 ).to.be.false;
+				expect( editingViewRoot.hasClass( 'ck-blurred' ), 10 ).to.be.true;
+				expect( secondEditingViewRoot.hasClass( 'ck-focused' ), 11 ).to.be.true;
+				expect( secondEditingViewRoot.hasClass( 'ck-blurred' ), 12 ).to.be.false;
+
+				secondEditableElement.remove();
 			} );
 		} );
 	} );