There used to be really great designer support for Windows 8.0 apps in Visual Studio 2012.  In the [Device Panel][Device Panel], you could move to different `VisualStates` within the `VisualStateManager.VisualStateGroups` on your page and it would update the appropriate properties at design time. 

In 8.1, the `VisualState`s are [no longer based on specific snapped layouts][responsive], but you can still use the `VisualStateManager` and update based on the screen `width`.

*Q*: How can I get these changes to update at design time?

-----


Here's a simple example of a change that works at runtime, but not design time.

**MainView.xaml.vb**:



    Private Sub MainView_Loaded(sender As Object, e As RoutedEventArgs) Handles Me.Loaded
        AddHandler Me.SizeChanged, AddressOf WindowSizeChanged
        ApplyViewState(Me.Width, Me.Height)
    End Sub

    Private Sub WindowSizeChanged(sender As Object, e As SizeChangedEventArgs)
        ApplyViewState(e.NewSize.Width, e.NewSize.Height)
    End Sub

    Private Sub ApplyViewState(ByVal viewWidth As Double, ByVal viewHeight As Double)
        If viewWidth < 350 Then
            VisualStateManager.GoToState(Me, "SmallLayout", True)
        Else
            VisualStateManager.GoToState(Me, "RegularLayout", True)
        End If
    End Sub

**MainView.xaml**:



    <Page x:Name="PageRoot"
        x:Class="WinStoreMvvmTemplate.View.MainView"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
        
        <Grid Background="Red" x:Name="ContentGrid">
            
            <VisualStateManager.VisualStateGroups>
                <VisualStateGroup>
                    <VisualState x:Name="RegularLayout"/>
                    <VisualState x:Name="SmallLayout">
                        <Storyboard>
                            <ObjectAnimationUsingKeyFrames 
                                Storyboard.TargetName="ContentGrid"
                                Storyboard.TargetProperty="Background">
                                <DiscreteObjectKeyFrame KeyTime="0" Value="Blue"/>
                            </ObjectAnimationUsingKeyFrames>
                        </Storyboard>
                    </VisualState>
                </VisualStateGroup>
            </VisualStateManager.VisualStateGroups>
    
        </Grid>
    </Page>


-----

Here's a view at **Design Time**: *(incorrect)*

![design][design]

Here's a view at **Run Time**: *(correct)*

![runtime][runtime]

[Device Panel]: http://msdn.microsoft.com/en-us/library/windows/apps/jj129464.aspx

[responsive]: http://blogs.windows.com/windows/b/appbuilder/archive/2013/07/02/build-talk-of-the-week-beautiful-apps-at-any-size-on-any-screen.aspx
[design]: http://i.imgur.com/hdZdAf7.png
[runtime]: http://i.imgur.com/XEpMUvr.png

How to get Designer Support for VisualStateGroups in Windows 8.1 XAML Apps

Using IsDateLastRecallPrintedNull isn't a workaround, it's the way it's intended to be used. If you use a nullable date, you can set this to nothing rather than DateTime.MinValue in your code. Alternatively you can change the datatype in the dataset to System.Object, and then you can select '(Nothing)'  in the dropdown. Note that you can overtype the NullValue entry in the properties with another value that's appropriate for the data type, although it won't work if you enter DateTime.Minvalue - it'll appear to accept it, but then fail - but you can put in another magic number such as 01/01/1900.

All this is 'by design'.*

Using databinding sidesteps this quagmire to a great extent; if you're reading programmatically from the dataset then IsxxxNull is the way to go.

*I suspect this is too often a Microsoftism for 'we didn't finish it by ship date'

When designing data tables in the .xsd designer in Visual Studio, there is a property that specifies what to do when the table encounters a null value:

![screenshot][screenshot]

The problem is, if the `DataType` is `System.DateTime`, I'm unable to return `empty` or `nothing`.  It always throws an exception.  

As I work around, I can do the following:



    If(row.IsDateLastRecallPrintedNull, DateTime.MinValue, row.DateLastRecallPrinted)


But if the value is `DbNull.Value`, I'd rather just have it return that.

[screenshot]: http://i.imgur.com/1hF0Lf1.png