binding:text block to listbox wpf - wpf

Question

I am new to WPF. I have this code
<Window x:Class="ElementBinding.MultipleBindings"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MultipleBindings" Height="320" Width="300">
<Grid>
<Slider Name="sliderFontSize" Margin="0,12,6,243"
Minimum="1" Maximum="40" Value="10"
TickFrequency="1" TickPlacement="TopLeft">
</Slider>
<TextBox Name="txtContent" Margin="0,44,0,208">Color should change here</TextBox>
<TextBlock Margin="3,150,3,3" Name="lblSampleText"
FontSize="{Binding ElementName=sliderFontSize, Path=Value}"
Text="{Binding ElementName=txtContent, Path=Text,Mode=TwoWay}"
Foreground="{Binding ElementName=lstColors, Path=SelectedItem.Tag}" >
Multiple Bindings
</TextBlock>
<ListBox Height="54" HorizontalAlignment="Left" Margin="12,90,0,0" Name="lstColors" VerticalAlignment="Top" Width="120" >
<ListBoxItem>Green</ListBoxItem>
<ListBoxItem>Red</ListBoxItem>
<ListBoxItem>Blue</ListBoxItem>
</ListBox>
</Grid>
</Window>
Text block will not appear if I select an item in list box. I think problem is in 'SelectedItem.Tag'. How can I resolve this?

Answer 1

You are correct. It should be Path=SelectedItem.Content:
<TextBlock Margin="3,150,3,3" Name="lblSampleText"
FontSize="{Binding ElementName=sliderFontSize, Path=Value}"
Text="{Binding ElementName=txtContent, Path=Text,Mode=TwoWay}"
Foreground="{Binding ElementName=lstColors, Path=SelectedItem.Content}" >

Answer 2

some advices
dont use just Margin to arrange your controls, look at Layout with Panels(Grid,DockPanel, and so on)
dont use the fontsize and a slider to create something like a zoom, better use LayoutTransform with ScaleTransform
at least Shakti is right the binding should be to SelectedItem.Content
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="auto" />
<RowDefinition Height="auto" />
<RowDefinition Height="auto" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Slider Name="sliderFontSize" Grid.Row="0" TickPlacement="TopLeft"
Minimum="1" Maximum="5" Value="1"
TickFrequency="1">
</Slider>
<TextBox Name="txtContent" Grid.Row="1">Color should change here</TextBox>
<TextBlock Grid.Row="3" Name="lblSampleText"
Text="{Binding ElementName=txtContent, Path=Text,Mode=TwoWay}"
Foreground="{Binding ElementName=lstColors, Path=SelectedItem.Content}" >
<TextBlock.LayoutTransform>
<ScaleTransform ScaleX="{Binding ElementName=sliderFontSize, Path=Value}" ScaleY="{Binding ElementName=sliderFontSize, Path=Value}"/>
</TextBlock.LayoutTransform>
</TextBlock>
<ListBox Height="54" HorizontalAlignment="Left" Name="lstColors" VerticalAlignment="Top" Width="120" Grid.Row="2">
<ListBoxItem>Green</ListBoxItem>
<ListBoxItem>Red</ListBoxItem>
<ListBoxItem>Blue</ListBoxItem>
</ListBox>
</Grid>