Decorator design pattern ( C++ )

#include <iostream>

using namespace std;

/* Component (interface) */
class Widget {

public:
   virtual void draw() = 0;
   virtual ~Widget() {}

};

/* ConcreteComponent */
class TextField : public Widget {

private:
    int width, height;

public:
    TextField( int w, int h ){
       width = w;
       height = h;
    }
   void draw() {
       cout << "TextField: " << width << ", " << height << '\n';
    }

};

/* Decorator (interface) */
class Decorator : public Widget {

private:
    Widget* wid; // reference to Widget
public:
    Decorator( Widget* w ) {
      wid = w;
    }
void draw() {
      wid->draw();
    }

~Decorator() {
      delete wid;
    }

};

/* ConcreteDecoratorA */
class BorderDecorator : public Decorator {

public:
    BorderDecorator( Widget* w ) : Decorator( w ) { }
    void draw() {
       Decorator::draw();
       cout << " BorderDecorator" << '\n';
    }

};

/* ConcreteDecoratorB */
class ScrollDecorator : public Decorator {
public:
    ScrollDecorator( Widget* w ) : Decorator( w ) { }
    void draw() {
       Decorator::draw();
       cout << " ScrollDecorator" << '\n';
    }

};

int main( void ) {

    Widget* aWidget = new BorderDecorator( new ScrollDecorator( new
TextField( 80, 24 )));

    aWidget->draw();

    delete aWidget;

}

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How does interface property changes here ?

it will call draw( ) function in following order
    1. TextField
    2. ScrollDecorator
    3. BorderDecorator

Is it Following RAII( Resource Acquisition is Order of
initialization ) principle of C++ ?

How are virtual function helping it ?

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