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System.AccessViolationException when trying to launch UWP program

I tried to make a new UWP app just to test things out, but now I'm stuck with this exception:
System.AccessViolationException: 'Attempted to read or write protected memory.
This is often an indication that other memory is corrupt.'
All I did after making new Solution, was to make few more pages and added this to the App() in order to achieve global back button:
public App()
{
this.InitializeComponent();
this.Suspending += OnSuspending;
var currentView = SystemNavigationManager.GetForCurrentView();
currentView.AppViewBackButtonVisibility = AppViewBackButtonVisibility.Visible;
Frame rootFrame = Window.Current.Content as Frame;
}
private void App_BackRequested(object sender, Windows.UI.Core.BackRequestedEventArgs e)
{
e.Handled = On_BackRequested();
}
And now, every time, it goes to this:
var currentView = SystemNavigationManager.GetForCurrentView();
I get this exception. I'm running out of ideas. Does anyone know what could cause this? In my Debugging settings I have unchecked the: "Suppress JIT opimization on module load" -setting, as suggested elsewhere, but that doesn't help.
Is there something that I don't understant of making an UWP-app, where you can click buttons at the top, and a page would change below them. Here's the XAML behind this:
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="2*"/>
<RowDefinition Height="10*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<StackPanel Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="3" x:Name="stackPanel_up" Orientation="Horizontal" HorizontalAlignment="Center"
VerticalAlignment="Center" Margin="10">
<Button x:Name="eka" Background="Aqua" Content="First" Width="200"
Height="50" FontSize="30" FontWeight="Bold" CornerRadius="10" Margin="5,0,5,0"
Click="eka_Click"/>
<Button x:Name="toka" Background="Aqua" Content="Second" Width="200" Height="50"
FontSize="30" FontWeight="Bold" CornerRadius="10" Margin="5,0,5,0"
Click="toka_Click"/>
<Button x:Name="kolmas" Background="Aqua" Content="Third" Width="200" Height="50"
FontSize="30" FontWeight="Bold" CornerRadius="10" Margin="5,0,5,0"
Click="kolmas_Click"/>
</StackPanel>
<Button Grid.Column="0" Grid.Row="0" x:Name="BackBtn" FontSize="50" Margin="40,0,0,0"
HorizontalAlignment="Left" Width="100" Height="100" CornerRadius="30"
Background="Transparent" Click="Back_Click" Style="{StaticResource NavigationBackButtonNormalStyle}" />
<Frame Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="3" x:Name="ChangingArea" Margin="10" Background="AliceBlue"></Frame>
</Grid>

WPF TextBox does not lose focus

I knwow there are many other who wrote about this but the suggested solutions don't solve my problem.
I've got a sort of gallery and I need that when the user edits the number specified in the TextBox automatically the image is updated.
Initially I tried with LostFocus event, but it doesn't always fire as explained here.
If I bind the property as suggested here, I have too many events if the number has more than one digit.
Then I tried to do this, but it doesn't work.
This is how my TextBox is defined:
<TextBox Margin="2" Text="{Binding NImageShown}" FontSize="18"
LostFocus="ImageIndex_OnLostFocus"
Name="ImageIndex" Height="40" Width="60"
VerticalAlignment="Center" VerticalContentAlignment="Center"
Focusable="True">
</TextBox>
I implemented the third solution by attaching the window to MouseDown event:
<Window x:Class="...."
.....
MouseDown="Window_MouseDown"....>
private void Window_MouseDown(object sender, MouseButtonEventArgs e)
{
if (ImageIndex.IsFocused)
Keyboard.ClearFocus();
}
With this solution I sawy that ImageIndex.IsFocused remains true even after Keyboard.ClearFocus(): this is the reason why I think that solution does not fix my problem.
Any help is really appreciate!
EDIT
Changes based on the suggestions:
<Grid Grid.Row="2" Grid.Column="2" Name="GridTextbox">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
.....
<StackPanel Grid.Column="2" Orientation="Horizontal"
HorizontalAlignment="Right">
<TextBox Margin="2" Text="{Binding NImageShown}" FontSize="18" LostFocus="ImageIndex_OnLostFocus"
Name="ImageIndex" Height="40" Width="60" VerticalAlignment="Center" VerticalContentAlignment="Center" Focusable="True"></TextBox>
<Label Style="{DynamicResource LabelStyle}" VerticalAlignment="Center"
Content="{Binding NTotalImages}" FontSize="18" Padding="5,0,5,0" Margin="5,5,5,5" />
</StackPanel>
</Grid>
private void Window_MouseDown(object sender, MouseButtonEventArgs e)
{
if (ImageIndex.IsFocused)
{
GridTextbox.Focus();
Keyboard.ClearFocus();
}
}
Even with these changes, LostFocus doesn't fire.
SOLUTION
Change the xaml as suggested in this way and keep the code behind as written before:
<TextBox Margin="2" Text="{Binding NImageShown}" FontSize="18"
LostKeyboardFocus="ImageIndex_OnLostFocus"
KeyDown="ImageIndex_OnLostFocus"
Name="ImageIndex" Height="40" Width="60"
VerticalAlignment="Center" VerticalContentAlignment="Center"
Focusable="True">
</TextBox>

Checkbox in ItemTemplate

I have a <Checkbox/> in my <GridView.ItemTemplate>. How do I handle the <Checkbox/> as to the element in which it is?
For example, I want to delete item when checkbox checked.
I think should write here. But what?
private void CheckBox_Checked_1(object sender, RoutedEventArgs e)
{
}
Here's My XAML:
<GridView Margin="0,10,0,0"
RelativePanel.AlignHorizontalCenterWithPanel="True"
x:Name="GridColections"
IsItemClickEnabled="True"
SelectionMode="None"
ItemsSource="{x:Bind DS.AllRem, Mode=OneWay}"
ItemClick="GridColections_ItemClick" >
<GridView.ItemTemplate>
<DataTemplate x:DataType="local:GetRem" >
<Grid Margin="-2,0,-6,0" BorderBrush="LightGray" BorderThickness="1" HorizontalAlignment="Stretch">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="40" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="30" />
<RowDefinition Height="30" />
</Grid.RowDefinitions>
<TextBlock TextTrimming="CharacterEllipsis" Grid.Column="0" Grid.Row="0" HorizontalAlignment="Stretch" TextWrapping="Wrap" Text="{x:Bind ReminderName}" Margin="5,5,0,0" FontSize="20"/>
<TextBlock TextTrimming="CharacterEllipsis" Grid.Column="0" Grid.Row="1" Width="600" TextWrapping="Wrap" Text="{x:Bind ReminderDescription}" Margin="5,5,0,0" FontSize="12"/>
<CheckBox Grid.Column="2" Grid.Row="0" Grid.RowSpan="2" VerticalAlignment="Center" Checked="CheckBox_Checked_1"/>
</Grid>
</DataTemplate>
</GridView.ItemTemplate>
</GridView>

The problem is that you almost certainly want to be able to use the DataContext in your click handler but you won't get that easily by just having a reference to the CheckBox which will be the sender argument in your callback. Normally what you would do here is create a Command on your item's view model and bind to that and any additional information that you would want to pass in you would pass in through the CheckBox's CommandParameter.
Once you do this you are now operating in your view model with a reference to whatever piece of information that you need through the command parameter (for instance you could set CommandParameter = "{Binding}" to pick up the entire data context which would be the item's view model and that would be accessible from your Command as an argument to it). You should be able to solve your issue this way.

Adding content to PivotItem dynamically

I have a page with a Pivot. It´s based on the Visual Studio Template.
<!--Pivot Control-->
<phone:Pivot SelectionChanged="evt_pivot_SelectionChanged">
<phone:Pivot.Title>
<StackPanel HorizontalAlignment="Center">
<!-- <TextBlock Text="MyApp" /> -->
<Image Stretch="None" HorizontalAlignment="Left" Margin="0" MinWidth="50" MaxHeight="50" Source="/mAppData/logo.png"/>
</StackPanel>
</phone:Pivot.Title>
<!--Pivot item one-->
<phone:PivotItem Header="Favoriten">
<!--Double line list with text wrapping-->
<phone:LongListSelector Margin="13,0,0,0" ItemsSource="{Binding Items}">
<phone:LongListSelector.ItemTemplate>
<DataTemplate>
<StackPanel Margin="0,0,0,25">
<Grid VerticalAlignment="Top">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="100" />
</Grid.ColumnDefinitions>
<TextBlock Grid.Column="0" Grid.ColumnSpan="2" Text="FELIX ClubRestaurant (Berlin)" TextWrapping="NoWrap" Style="{StaticResource PhoneTextLargeStyle}" VerticalAlignment="Top" Margin="0,0,0,22" />
<Image Grid.Column="0" Width="110" Height="20" Source="/mAppData/stars-3.png" HorizontalAlignment="Left" VerticalAlignment="Bottom" Margin="0"/>
<TextBlock Grid.Column="1" Text="10 min." TextWrapping="NoWrap" Margin="0" Style="{StaticResource PhoneTextSubtleStyle}" HorizontalAlignment="Right" VerticalAlignment="Bottom"/>
</Grid>
<Grid VerticalAlignment="Top" Margin="0,10,0,0">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Image Grid.Column="0" Width="100" Height="100" Source="http://img.myserver.net/news-teaser//p189j19861b36c5d1pp012i21grgd.gif"/>
<Image Grid.Column="1" Width="100" Height="100" Source="http://img.myserver.net/news-teaser//p187qrndfcj0la0f12clfkv10ec7.gif"/>
<Image Grid.Column="2" Width="100" Height="100" Source="http://img.myserver.net/news-teaser/005e5d03f058fa8f7bd95f6410dfc6d6.gif"/>
<Image Grid.Column="3" Width="100" Height="100" Source="http://img.myserver.net/news-teaser/3c05cbf76fba7ada5182b4426e55d96b.gif"/>
</Grid>
</StackPanel>
</DataTemplate>
</phone:LongListSelector.ItemTemplate>
</phone:LongListSelector>
</phone:PivotItem>
<!--Pivot item two-->
<phone:PivotItem Header="Empfohlen">
</phone:PivotItem>
</phone:Pivot>
I added in CodeBehind the handling for the event SelectionChanged. That works fine. So I can capture by code, when user comes to the second PivotItem.
private async void evt_pivot_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
int mPivotIndex = Convert.ToInt16(((Pivot)sender).SelectedIndex.ToString());
if (mPivotIndex == 1)
{
// HERE I WANT TO INSERT THE SOLUTION
}
}
Now comes my problem: When user navigates to seconds item, I want to:
request some data from an WebService (this in not the problem)
transform the data (this is not the problem) and
populate the data in a LongListSelector (THIS IS MY PROBLEM PART 1)
In case that an error occures, I want not to display the LongListSelector but a TextBox showing a message (THIS IS MY PROBLEM PART 2)
How can I get my 2 problems get working?

You will need to bind the text/content of your controls in the itemtemplate to the data collection fieldname
Text="{Binding Fieldname}"
http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj207023(v=vs.105).aspx
In your error handling, set the visibility of the Longlistselector to Collapsed. Then you can show another control which displays the textbox
<StackPanel>
<LongListSelector x:Name=”MyListSelector”>
..stuff
</LongListSelector>
<TextBlock x:Name=”MyError” Visibility=”Collapsed”> </TextBlock>
</StackPanel>
Catch (Exception Ex)
{
MyListSelector.Visibility = Visibility.Collapsed
MyError.Visibility = Visibility.Visible
MyError.Text = Ex.Message;
}

you can hide the Longlist selector and add the Textbox with the Error message directly from the code behind. see the code below.
try
{
//make the service call and do your stuff
}
catch(exception ex)
{
MyListSelector.Visibility = Visibility.Collapsed;
var errorTextBox = new TextBox();
errorTextBox.Text = "some Error has occured";
//add all the properties you want to add for textbox such as color,height,fontsiz ect..
//Name your pivotitem control, say pivotitem1
pivotitem1.Content = errorTextBox;
}
hope this helps.
Note: uncompiled code. pardon compilation errors

Accessing mediaelement in listbox wp7

I have a MediaElement inside ListBox.How I can get access to "audiop_Copy" by buttons "play/pause"?
<local:TypeTemplateSelector.WithAudio>
<DataTemplate>
<Grid Margin="0,5">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<StackPanel Grid.Column="1">
<TextBlock ... />
<StackPanel Height="50" Orientation="Horizontal" Margin="5,0,4,0" MinHeight="50">
</TextBlock>
<Button Click="PlayMedia" Content="Play" />
<Button Click="PauseMedia" Content="Pause" />
</StackPanel>
<MediaElement Name="audiop_Copy" Source="{Binding audioUri}" Stretch="None" HorizontalAlignment="Left" AutoPlay="False"/>
</StackPanel>
</Grid>
</DataTemplate>
</local:TypeTemplateSelector.WithAudio>

2 ways to do it from the spot (possibly there are more). You will need a pointer to your Button that was clicked anyway:
[difficult, inflexible, fragile] In button Click event handler use VisualTreeHelper class to navigate Visual Tree and find the element. Use sender as starting point
[better solution] use Tag property and binding.
<Button Click="PauseMedia" Content="Pause" Tag={Binding ElementName=audiop_Copy} />
And in handler something like that:
private void PauseMedia(object sender, RoutedEventArgs e)
{
var me = ((FrameworkElement) sender).Tag as MediaElement;
}