The placeholder will not be shown over widgets.

src/view/placeholder.js

@@ -153,6 +153,11 @@ export function needsPlaceholder( element ) {
 		return false;
 	}
 
+	// If the element is a Widget always consider it a non-empty and thus not needing a placeholder.
+	if ( element.getCustomProperty( 'widget' ) ) {
+		return false;
+	}
+
 	// The element is empty only as long as it contains nothing but uiElements.
 	const isEmptyish = !Array.from( element.getChildren() )
 		.some( element => !element.is( 'uiElement' ) );

tests/view/placeholder.js

@@ -389,6 +389,20 @@ describe( 'placeholder', () => {
 			expect( needsPlaceholder( element ) ).to.be.false;
 		} );
 
+		it( 'should return false if element is a widget', () => {
+			// Widget with ui-only elements inside (emptyish).
+			setData( view, '<div><ui:span></ui:span></div>' );
+			viewDocument.isFocused = false;
+
+			const element = viewRoot.getChild( 0 );
+
+			view.change( writer => {
+				writer.setCustomProperty( 'widget', true, element );
+			} );
+
+			expect( needsPlaceholder( element ) ).to.be.false;
+		} );
+
 		it( 'should return true if element is empty and document is blurred', () => {
 			setData( view, '<p></p>' );
 			viewDocument.isFocused = false;