Event bubbling in Asp.Net

Handling(tracking) child controls events (only button type child controls) through parent control in data bind controls known as event bubbling.

Server controls like Datagrid, DataList, and Repeater can have other child controls inside them.

Example DataGrid can have combo box inside datagrid. These child control do not raise there events by themselves, rather they pass the event to the container parent (which can be a datagrid,
datalist, repeater), which passed to the page as "ItemCommand" event. As the child control send events to parent it is termed as event bubbling.

CODE:
Basically, to raise the event that you want bubbled up:

RaiseBubbleEvent(this, args);
And then to catch it:

protected override bool OnBubbleEvent(object source, EventArgs e) {
    bool handled = false;

    if (e is TemplatedListCommandEventArgs) {
        TemplatedListCommandEventArgs ce = (TemplatedListCommandEventArgs)e;

        OnItemCommand(ce);
        handled = true;
    }
    return handled;
}
As the code implies, if this method returns false, the event will continue to bubble up the control hierarchy

LINK

Virtual vs Override vs New Keyword in C#

Virtual Keyword

Virtual keyword is used for generating a virtual path for its derived classes on implementing method overriding. Virtual keyword is used within a set with override keyword. It is used as:

// Base Class
    class A
    {
        public virtual void show()
        {
            Console.WriteLine("Hello: Base Class!");
            Console.ReadLine();
        }
    }


Override Keyword

Override keyword is used in the derived class of the base class in order to override the base class method. Override keyword is used with virtual keyword, as:

// Base Class
    class A
    {
        public virtual void show()
        {
            Console.WriteLine("Hello: Base Class!");
            Console.ReadLine();
        }
    }

// Derived Class

    class B : A
    {
        public override void show()
        {
            Console.WriteLine("Hello: Derived Class!");
            Console.ReadLine();
        }
    }

New Keyword

New keyword is also used in polymorphism concept, but in the case of method overloading So what does overloading means, in simple words we can say procedure of hiding your base class through your derived class.

It is implemented as:

class A
    {
        public void show()
        {
            Console.WriteLine("Hello: Base Class!");
            Console.ReadLine();
        }
    }

    class B : A
    {
        public new void show()
        {
            Console.WriteLine("Hello: Derived Class!");
            Console.ReadLine();
        }
    }


Example:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Generics
{
    class A
    {
        public void show()
        {
            Console.WriteLine("Hello: Base Class!");
            Console.ReadLine();
        }
    }

    class B : A
    {
        public void show()
        {
            Console.WriteLine("Hello: Derived Class!");
            Console.ReadLine();
        }
    }

    class Polymorphism
    {
        public static void Main()
        {
            A a1 = new A();
            a1.show();
            B b1 = new B();
            b1.show();
            A a2 = new B();
            a2.show();

        }
    }
}


Output :
Hello: Base Class!
Hello: Derived Class!
Hello: Base Class!