Paddingoutside the widget
Containeritself is a bit of a beginner tool. It's very useful to give beginner a foothold into the system, but most developers end up using the component pieces directly as they become more advance because that's the more flexible/powerful approach
Paddingtends to be the stepping stone in that direction
child: new RichText( text: new TextSpan( children: <TextSpan>[ new TextSpan( style: aboutTextStyle, text: "Flutter is an early-stage, open-source project to help " "developers build high-performance, high-fidelity, mobile " "apps for iOS and Android from a single codebase. This " "gallery is a preview of Flutter's many widgets, behaviors, " "animations, layouts, and more. Learn more about Flutter at " ), new LinkTextSpan( style: linkStyle, url: 'https://flutter.io' ), new TextSpan( style: aboutTextStyle, text: ".\n\nTo see the source code for this app, please visit the " ), new LinkTextSpan( style: linkStyle, url: 'https://goo.gl/iv1p4G', text: 'flutter github repo' ), new TextSpan( style: aboutTextStyle, text: "." ) ] ) )
The constructor returns type 'dynamic' that isn't of expected type 'TextSpan'