This event handler method gets called once per frame.
对每帧调用一次此事件处理程序方法。
2
This event handler gets called once per frame.
每个画面格都会呼叫此事件处理常式一次。
3
The main frame creates all the toolbars at the beginning of the program, i. e. in the OnCreate message handler, and the toolbars are children of the main frame.