Visual Basic 2015 Unleashed

Implementing Cancellation

Let’s look at the WPF sample application created in the section “Getting Started with Async/Await.” Imagine you want to give users the ability of cancelling the download of the RSS feed from the Microsoft Channel9 website. First, make a slight modification to the user interface so that the main Grid is divided into two rows, and in the first row add a Button like this:

Click here to view code image

<Grid.RowDefinitions>    <RowDefinition Height="40"/>    <RowDefinition/></Grid.RowDefinitions><Button Width="120" Height="30" Name="CancelButton"        Content="Cancel"/>

Do not forget to add the Grid.Row="1" property assignment for the ListBox control. Double-click the new button so that you can quickly access the code ...