2. How to show the SIP keyboard in xna app?

This is not in the CTP, but will be in later builds: Guide.BeginShowKeyboardInput

3. Explain starting with April CTP Refresh, I can compile and debug my XNA game, but it does not show up in list of applications when I am not launching it on the debugger?

The games are installed in games hub, which you can't see in the currently slimmed image. Change the Genre attribute in the App element in WindowsPhoneManifest.xml from App.Games to NormalApp
<App xmlns="" ... RuntimeType="XNA" Version="1.0.0.0" Genre="NormalApp" >

4. Suppose when I deployed my XNA app to the xDE, the orientation is in portrait mode, but when I deploy it to a device, it's in landscape mode.?

The XNA Framework defaults to landscape mode for Windows Phone games, but XDE doesn't yet support XNA in landscape mode, so portrait mode is the only option there for now. You can set your orientation preferences by using GraphicsDeviceManager settings (SupportedOrientations, PreferredBackBufferHeight, PreferredBackBufferWidth, etc.

5. Tell me is it possible to use Custom Pixel Shader in XNA?

From Shawn Hargreaves blog For this release, there are no programmable shaders: “Instead of programmable shaders, we augmented the existing BasicEffect with four new configurable effects: SkinnedEffect, EnvironmentMapEffect, DualTextureEffect, and AlphaTestEffect. These are designed to run efficiently on the mobile GPU hardware, and I think do a good job of providing enough flexibility for developers to create awesome looking games, while also meeting our goals of being able to ship a robust and well tested product on schedule.”

6. Tell me are there canned MVVM "Data Behaviors" planned for WP7?

Not at this time. The behaviors have dependencies in Silverlight 4.

7. Suppose Have a very simple application that uses the APplicationBar. The app bar shows one menu item when in portrait. However as the second image shows the app bar displays now items in landscape mode. Is that by design or a bug?

Yes, it's a known problem in the emulator on machines that don't support the hardware accelerated graphics in the emulator. It works properly on devices and machines that do

8. Tell me is it possible to run two instances of emulator on the same machine. I am doing some networking app and need two emulators to test it?

You can not launch two instances from the Phone tools. You can launch a second instance from command line.
c:Program Files (x86)Microsoft XDE1.0XDE.exe" "C:Program Files (x86)Microsoft SDKsWindowsPhonev7.0EmulationImagesWM70C1.bin"

9. Suppose I have lost one of the application templates in Visual Studio 2010. It's available in the file system but not in Visual Studio… Any ideas?

Try running Devenv /setup.
Running devenv /installvstemplate might also work; but that is going to slow down overall VS performance. The /installvstemplate is a development only option that makes it easy for developer to test their templates. This shouldn't be used on end user machines. Devenv /setup does a lot of more processing and caching to speed up VS performance.

10. in the emulator, NetworkInterface.GetIsNetworkAvailable() always return false?

This is a known bug in MIX CTP and April refresh. Sorry! It will be addressed in next build

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