VCL消息(一)

消息流程：

PostMessage：立即返回，Application.OnMessage-->WndProc-->用户消息影射函数-->DefaultHandler

SendMessage：等待返回，WndProc-->用户消息影射函数-->DefaultHandler

TMainForm = class(TForm)

private

  procedure OnAppMessage(var Msg: TMsg; var Handled: Boolean);

procedure WndProc(var Msg: TMessage); override;

procedure MyMessage(var Msg: TMessage); message MY_MESSAGE;

procedure DefaultHandler(var Msg); override;

end;