Develop Reference

Setting VerticalContentAlignment in my WPF TabItem changes both the text in the tab and the Control contained in the tab

<TabItem Header="Data Entry"
FontSize="40"
VerticalContentAlignment="Top"
HorizontalContentAlignment="Center"
VerticalAlignment="Center"
Height="75"
Width="300"
Background="#464646"
Foreground="White"
DataContext="{Binding Tabs[0]}">
<Controls:DataEntryUserControl />
</TabItem>
My TabItem is formed with the code above. I want the text in the tab ("Data Entry") to be aligned to the center of the tab, but I want the UserControl to be aligned to the top of the window. However, both of these alignments change when I set VerticalContentAlignment (e.g. in the code above, both of them are aligned to the top of their respective parents). The VerticalAlignment property doesn't change anything.
How can I accomplish this?

Define a HeaderTemplate where you specify the alignment of the header:
<TabItem Header="Data Entry"
FontSize="40"
Height="75"
Width="300"
Background="#464646"
Foreground="White"
DataContext="{Binding Tabs[0]}">
<TabItem.HeaderTemplate>
<DataTemplate>
<TextBlock Text="{Binding}" HorizontalAlignment="Center" />
</DataTemplate>
</TabItem.HeaderTemplate>
<Controls:DataEntryUserControl />
</TabItem>

WPF Textblock With Bound Text Will Not Scroll

The text in my TextBlock is bound to an element in my code. However, when I first open my window, the Textblock is completely empty. As I add text, I need the ScrollViewer to allow me to scroll down the text, or automatically scroll down as more text is added. Using the MVVM, so no code behind would be ideal.
<StackPanel Grid.Column="0" Grid.Row="1" Margin="0 10">
<Label Style="{StaticResource LabelStyle}">Output</Label>
<ScrollViewer VerticalScrollBarVisibility="Visible" Height="100">
<TextBlock ScrollViewer.CanContentScroll="True" Height="100" VerticalAlignment="Stretch" TextWrapping="Wrap" Text="{Binding Path=ProcessingOutput}"/>
</ScrollViewer>
</StackPanel>
How can I make this happen? Is there a way to update the ScrollViewer so that it sees more text is beyond what I can see in the TextBlock and allows the user to scroll down, or allows me to set an autoscroll feature that scrolls down automatically as text is added via binding?
Thanks in advance!

scrollbar will work if you remove Height="100" from TextBlock
to make it scroll when Text changes other answers suggest to use ScrollViwer.ScrollToBottom() method, e.g. like this:
<ScrollViewer Name="scroll"
VerticalScrollBarVisibility="Visible"
Height="100">
<TextBlock ScrollViewer.CanContentScroll="True"
VerticalAlignment="Stretch"
TextWrapping="Wrap"
Text="{Binding Path=ProcessingOutput, NotifyOnTargetUpdated=True}"
TargetUpdated="Txt_OnTargetUpdated">
</TextBlock>
</ScrollViewer>
private void Txt_OnTargetUpdated(object sender, DataTransferEventArgs e)
{
scroll.ScrollToBottom();
}

C# XAML Listbox collapse when clicked

I'm new in XAML for Windows Phone 8.1 and have some troubles with
making a Stackpanel clickable
collapse Item, when clicked
My work so far looks like that:
And the Code to that (please correct me, if there are major flaws):
<Border CornerRadius="15" Background="#FF595656" Margin="0" Grid.ColumnSpan="2" Height="80">
<StackPanel Orientation="Horizontal">
<StackPanel Width="20" HorizontalAlignment="Left" VerticalAlignment="Top" />
<StackPanel HorizontalAlignment="Left" Height="80" Margin="0,0,0,0" VerticalAlignment="Center" Width="51">
<Image HorizontalAlignment="Left" Height="51" Margin="0,15,0,0" Width="51" Source="Assets/fish.png" Stretch="Fill" RenderTransformOrigin="2.307,0.881" VerticalAlignment="Center"/>
</StackPanel>
<StackPanel Width="10" HorizontalAlignment="Left" VerticalAlignment="Top" />
<StackPanel HorizontalAlignment="Left" Height="80" Margin="0" VerticalAlignment="Top" Width="310">
<TextBlock HorizontalAlignment="Left" Height="25" Margin="0,20,0,0" TextWrapping="Wrap" Text="Entry 1" Width="310" VerticalAlignment="Top" FontSize="18" Foreground="Black" FontWeight="Bold"/>
<TextBlock HorizontalAlignment="Left" Height="17" Margin="0" TextWrapping="Wrap" Text="Short description Entry 1" Width="310" VerticalAlignment="Top" Foreground="#FF0097FF"/>
</StackPanel>
</StackPanel>
</Border>
This code will later be wrapped inside a ListBox with Image, Entry 1 and the short description being bound:
<ListBox x:Name="ListBox1" Margin="0"
Width="400" Height="200" HorizontalAlignment="Left"
ItemsSource="{Binding}" Grid.Row="1" VerticalAlignment="Top" Grid.ColumnSpan="2" >
<ListBox.ItemTemplate>
<DataTemplate>
// the code above
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
So my question is:
How can I make a nice looking expansion/collapse of each Item in the ListBox, whenever I click on it?
Thank you very much in advance.

The real question is here is what do you want it to collapse to? There are too many possible ways to collapse some visual data item. Do you just want to change the height of the item or do you want some fancy animation that collapse some property?
If the height is what you're looking for it's pretty easy. Just attach an Tap Event on that Border of yours. On a sidenote, you probably want to edit the ItemContainerStyle to have <Setter Property="HorizontalContentAlignment" Value="Stretch"/> so the Listbox will stretch across the screen, otherwise imho it's un-useable.
<ListBox.ItemTemplate>
<DataTemplate>
<Border BorderBrush="Red" BorderThickness="0,1" Tap="Border_Tap">
<StackPanel>
<!--- rest of template --->
</StackPanel>
</Border>
</DataTemplate>
</ListBox.ItemTemplate>
Then calculate the Minimum height you want to show (make sure it's actually useable, meaning... I can Tap on it again to show the whole thing without using a Mag Glass).
private void Border_Tap(object sender, System.Windows.Input.GestureEventArgs e)
{
int minHeight = 40; // change to whatever you want
Border b = sender as Border;
if (b.ActualHeight > minHeight)
{
b.Height = minHeight;
}
else
{
b.Height = double.NaN; // this will change the height back to Auto, showing everything
}
}
Code In Action
This is just a quick solution to your question. Some people on here would rather have you create a StoryBoard Animation on the Height Property of the Selected state in the VisualStateManager. If you reword or create a new question explicitly stating you want a VisualStateManager solution, I will provide you one as well. Good luck.

How to make ScrollViewer work only when texblock in it has height greater than ScrollViewer height?

In my ListBox I show different content including text. Text can be long or short. It scrolls by ScrollViewer. Code:
<ScrollViewer MaxHeight="300" VerticalAlignment="Top" Grid.Column="1" Grid.Row="1" >
<TextBlock Style="{StaticResource TextsTextBlock}" Text="{Binding Texts}" Grid.Column="1" Grid.Row="1" />
</ScrollViewer>
and it's also working if text is short, and height of this text do not reach MaxHeight of ScrollViewer. I want to make ScrollViewer works only when text is long and it's height greater than ScrollViewer's MaxHeight, else - it doesn't have to work.
Tried border
<Border BorderBrush="Aqua" BorderThickness="2" MaxHeight="300" VerticalAlignment="Top" Grid.Column="1" Grid.Row="1">
<ScrollViewer VerticalAlignment="Top" VerticalScrollBarVisibility="Auto" >
<TextBlock Style="{StaticResource TextsTextBlock}" Text="{Binding Texts}" Grid.Column="1" Grid.Row="1" />
</ScrollViewer>
</Border>
but it's still scrolls in this border.

Set the VerticalScrollBarVisibility property to Auto.
The default value is Visible which means that the scroll bar is always shown.
By contrast the HorizontalScrollBarVisibility property has a default value of Hidden.

Try removing some of the Grid. properties from the inner controls
<Border BorderBrush="Aqua" BorderThickness="2" MaxHeight="300" VerticalAlignment="Top" Grid.Column="1" Grid.Row="1">
<ScrollViewer VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Disabled" >
<TextBlock Text="text" TextWrapping="Wrap"/>
</ScrollViewer>
</Border>
this works fine with one line of text
If I copy paste your code it works fine

Listbox extending off the page

I have a listbox inside of a stack panel inside of a border in a silverlight application and when ever I add anything to the listbox it increases in height so the scrollbar is never used and it extends beyond the boundaries of the border element. I have tried explicitly setting the height attribute of the listbox, the border and the stack panel and it still goes beyond this.
Here is my code:
<Border x:Name="articlePane">
<StackPanel>
<StackPanel Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Top">
<Button Content="Latest" MouseEnter="HandleRollInAnimation" MouseLeave="HandleRollOutAnimation" />
<Button Content="Pending" MouseEnter="HandleRollInAnimation" MouseLeave="HandleRollOutAnimation" />
<Button Content="Done" MouseEnter="HandleRollInAnimation" MouseLeave="HandleRollOutAnimation" />
</StackPanel>
<ListBox x:Name="articleList" Margin="5" Background="Transparent" ItemsSource="{Binding}"
ScrollViewer.VerticalScrollBarVisibility="Visible">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Vertical" VerticalAlignment="Top" HorizontalAlignment="Center">
<Image x:Name="articleImage" />
<TextBlock x:Name="articleTitle" Text="{Binding Path=Title}" FontSize="18" FontWeight="Bold"
Margin="5"/>
<TextBlock x:Name="articleDate" Text="{Binding Path=Date}" FontSize="14" Foreground="Gray"
Margin="5"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</StackPanel>
</Border>

I have a feeling that the StackPanel just keeps on adding height forever. I think in this instance you'd be better off with a Grid layout within your Border. Put the Button StackPanel in one height defined row, and the ListBox in an autosizing * height row. This way Grid will stick within the confines of your form.