Signals and slots are used for communication between objects. The signals and slots mechanism is a central feature of Qt and probably the part that differs most from the features provided by other frameworks.
In GUI programming, when we ...
標準 C++ 對象模型為對象範式，提供瞭非常有效的運行時支持。但其靜態性質在某些問題領域是不靈活的。GUI (圖形用戶界麵) 編程要求運行時高效，且高級靈活性的兩者領域。Qt 通過組閤 C++ 的速度與 Qt 對象模型的靈活性，提供這。
The Qt layout system provides a simple and powerful way of specifying the layout of child widgets.
By specifying the logical layout once, you get the following benefits:
