WindowsPhone KeyBoard: Prevent page screen scrolling up when soft keyboard is opened(C#-XAML)

Problem:
​Generally in windows phone when TextBox is focus soft-keyboard will be open ,but here problem is by default page screen to shift upwards when keyboard opened and again shift previous position when user closed the keyboard by tap on screen.Actually this question is raised at MSDN WindowsPhone Development Forums.Even  lot of times this question is raised by developers and however more resource's available for solving this issue. 
   Requirement :Page UI having header,body and footer. In page UI there is a TextBox  just above the footer. When user focus on this TextBox the page header is going to invisible.But user doesn't want to page header shift upwards when keyboard is opened

Note: This Sample is targeted on WindowsPhone 7.1

Windows Phone 8 development shortcut keys with keyboard

Introduction

The Windows Phone 8  SDK comes with some shortcut keys for emulator .It would be very helpful for us to speedup our development process.1.WindowsPhone Emulator Screen unlock

    1.1. To lock the screen in the emulator by using the keyboard

•     With the emulator open, press F12 on your computer keyboard twice.
  The F12 key emulates the power button on the phone. The first key press turns off the display. The second key press turns the display on again with the lock screen engaged.
  You can unlock the screen by using the mouse to slide the lock screen upward.