This document provides an overview of developing cross-platform apps using Qt and Qyoto. It discusses what Qt is, how it is cross-platform, and how Qyoto works with Qt. It covers Qt concepts like signals and slots, properties, events, and model-view. It also discusses getting started with Qt Creator, examples of C# code using Qyoto, and demos of using MonoDevelop with Qyoto. Lastly, it briefly discusses Qt on Android and iOS, and the vision and architecture changes for Qt 5.