1. Where did the constructor of the Form1 is called? , in Application.CreateForm(TForm1, Form1); ?
That's not the constructor
per se but yes, it's where the form's
Create() is called among other things ... which lead us to:
2. How constructor of Form1 object call constructor of Button1 without the need to
override the constructor of TForm?
It's not the "constructor" of the form but the
CreateForm() method of TApplication. Very,
very basically, after some convolutions and among other things, the form resource (let's say, the
.lfm embedded in the program) is read, the form's properties set from it, controls and components (classes) read, instances created and properties set from it, etc.