sender 告诉用户当前谁在调用这个过程,应该是对象或类。
The Sender parameter in an event handler informs Delphi which component
received the event, and therefore called the handler. You can write a
single event handler that responds to multiple component events by using
the Sender parameter in an if..then..else statement.
帮助里有例子啊。
procedure TMain1.Button1Click(Sender: TObject);
begin
if Sender = Button1 then
AboutBox.Caption := 'About ' + Application.Title
else AboutBox.Caption := '';
AboutBox.ShowModal;
end;
