Question

I am trying to use a but am getting the error:
The property ‘Content’ is set more than once.
It dissappears if I remove any one of the two lines of code in between the tags.
So neither of them seems wrong individually, but both together cause the problem.

<Grid x:Name="LayoutRoot" Background="Transparent">

    <Grid.RowDefinitions>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>

    <!--TitlePanel contains the name of the application and page title-->
    <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
        <TextBlock x:Name="ApplicationTitle" Text="New Trip" Style="{StaticResource PhoneTextNormalStyle}" Height="40" />
        <Button Content="Back" Height="71" Name="button1" Width="103" HorizontalContentAlignment="Stretch" VerticalAlignment="Top" HorizontalAlignment="Right" Click="button1_Click" />
    </StackPanel>

    <!--ContentPanel - place additional content here-->
    <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
        <ScrollViewer>
            <TextBlock Height="60" HorizontalAlignment="Left" Margin="65,12,0,0" Name="textBlock1" Text="Username" VerticalAlignment="Top" Width="169" />
            <TextBox Height="78" HorizontalAlignment="Left" Margin="60,60,0,0" Name="textBoxUsername"  VerticalAlignment="Top" Width="274"  />
        </ScrollViewer>
    </Grid>

</Grid>

Answer 1

ScrollViewer can only have 1 content, so wrap the controls inside the ScrollViewer in a container like Grid, DockPanel, StackPanel

      <ScrollViewer>
        <StackPanel>
            <TextBlock Height="60" HorizontalAlignment="Left" Margin="65,12,0,0" Name="textBlock1" Text="Username" VerticalAlignment="Top" Width="169" />
            <TextBox Height="78" HorizontalAlignment="Left" Margin="60,60,0,0" Name="textBoxUsername"  VerticalAlignment="Top" Width="274"  />
        </StackPanel>
      </ScrollViewer>