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In this third WP7 programming tip, Jeff Prosise demonstrates how to disable an application bar button in code.

Source: Jeff Prosise's Blog

Application bars play an important role in the UI of many phone applications. An application bar can contain up to four buttons (and five menu items) giving the user quick and easy access to the app’s most commonly used features.

Each button is an instance of ApplicationBarIconButton, and the ApplicationBarIconButton class exposes a property named IsEnabled that allows buttons to be enabled and disabled.

See more Windows Phone programming tips by Jeff:

• Silverlight for Windows Phone Programming Tip #1
• Silverlight for Windows Phone Programming Tip #2

Watch the recording of SilverlightShow webinar 'Building Line-of-business Applications with Silverlight and WCF Data Services' delivered on February 23rd by Emil Stoychev.

In this session, Silverlight MVP Emil Stoychev went through the basics of the OData protocol, dived into WCF DataServices client for Silverlight and focused on key scenarios in LOB applications like lazy loading, dynamic queries, filtering/sorting/grouping/paging on the client and on the server, change tracking.

Sign up as a Silverlight Show member to get notified about next scheduled SilverlightShow webinars. Or, visit our webinars page.

Jeff Prosise has two blog posts discussing tombstoning in Silverlight for WP7:

• Tombstoning Pivot Controls in Silverlight for Windows Phone 
• Tombstoning Panorama Controls in Silverlight for Windows Phone 

  What is tombstoning? In short, while Windows phones are perfectly capable of running several applications at once, only OEMs can write apps that run in the background. Apps written by ordinary mortals can only run one at a time. If the user switches away from your app by, say, pressing the phone’s Start button, your app is terminated. To be more precise, the app is deactivated, and if the user next presses the Back button, the app is reactivated. But because deactivation really does mean the app was terminated, all state – including the state of the app’s controls – is lost. We refer to the deactivation-reactivation cycle as tombstoning.

   

In this video Jeff Wilcox shares some thoughts on his experience with writing the WP7 App Platform in C# and C++.

Source: Channel 9

Jeff Wilcox is a developer on the Silverlight team. He spends a lot of his time (~80%) coding in C++. Strange? Of course not... Silverlight is a portable managed runtime and C++ (C with classes in this case) is what enables Silverlight portability. Of course, Jeff also spends a significant amount of his time writing the managed parts of Silverlight (controls, libraries, etc.). He is an expert in both the managed and native programming models and he's responsible for some of the really powerful and widely used Silverlight controls that you employ when you're programming WP7 devices or Silverlight apps for Windows or OSX. Jeff is a code-cranking machine and a very talented software engineer. Code on, Jeff!

Also don't miss this interview with Jeff taken exclusively for all SilverlightShow fans by Emil Stoychev during MIX11.

Matt Lacey has a nice advice to all WP7 devs who want to make the size of their XAP file as small as possible... with a little help from Telerik!

Source: Matt Lacey's Blog

For an app I've been working on recently (more off than on) I wanted to get the start up time as short as possible. One of the ways I've been doing this has been to remove unnecessary external libraries and to optimise my use of the ones that I do need.

Now, while I'm a big fan of NuGet sometimes I don't want everything in a library. In this instance I created a version of the library I was using specifically restricted to the functionality that the app needs. I did this by getting the source of the library I was using (well actually libraries as there were 2), added the source project to my solution, excluded everything I didn't need from the project and then linked my app to that project rather than the downloaded copy of the compiled library.

There are always two situations which could break your application:

1. if there are no “ID” parameters in the url
2. if there is an “ID” parameter in the url, but it has a string value instead of an integer number.

To avoid breaking the code and causing runtime error we need to add a few conditions and also parse the value to integer instead of assigning it right away.

Source: Channel 9

This is a great episode to watch and the first in a periodic series from the RIA Services team in which we will address the top questions from developers.

This blog pots of Lee is on Custom Commands in Silverlight and Prism 4.

Source: Lee's corner

Silverlight 4 includes commanding support for ButtonBase classes, but for anything else we would need to write a little bit of code.

There is a nice section here on how to extend this to other situations. Here is a quick sample on how to create command support for MouseLeftButtonDown on an UIElement. You can download the code from here.

Microsoft announced their contest named "Hey Windows Phone, I need this app". If you have a great idea for a smartphone application, but you don't have the skills or connections - this contest is just for you! Microsoft will hear your ideas. If they like it, they will develop and release it and you will be 5000$ richer with a new Windows Phone 7 phone :)

The contest has started today and will be closed on 8th of July 2010. So you have a month to think. Stop browsing and get thinking now!

Here is the official page of the contest.