I am trying to create my own ToolTip layout like this:

                            <ToolTipService.ToolTip>
                                <StackPanel>
                                    <TextBlock Text="{Binding Title}" />
                                </StackPanel>
                            </ToolTipService.ToolTip>

 But it doesn't seem to work, it displays a small part of a tooltip (a small horizontal line), it appears like the binding does not work and tooltip text is empty "".

If I replace with a text instead (no data binding), obviously, it works:

                             <ToolTipService.ToolTip>
                                <StackPanel>
                                    <TextBlock Text="AAA" />
                                </StackPanel>
                            </ToolTipService.ToolTip>

 Furthermore, if I use the ToolTipService.ToolTip as an attached property it works:     

ToolTipService.ToolTip="{Binding Title}".

So the binding does work.

It seems that the tooltip doesn't work when I am trying to define the layout AND use data binding

Have you used tooltip with layout and data binding successfully ?

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Hi,

Can you show how you set an data item to your element?

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Sincerely,
Sergey Lutay

 Yes, thanks for your comment.

I've made a simple test application. I created a new Silverlight application and added a Button on the Page:

<UserControl x:Class="TooltipDataBindingTest.Page"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Width="400" Height="300">
    <Grid x:Name="LayoutRoot" Background="White">
        <Button x:Name="btn" Content="Caption" Width="100" Height="30" ToolTipService.ToolTip="{Binding Name}">
            <!-- The following does NOT work:-->
            <!--
            <ToolTipService.ToolTip>
                <TextBlock Text="{Binding Name}" />
            </ToolTipService.ToolTip> -->
        </Button>
    </Grid>
</UserControl>

Binding is defined like this:

    public class Person
    {
        public string Name
        {
            get;
            set;
        }
    } 

namespace TooltipDataBindingTest
{
    public partial class Page : UserControl
    {
        public Page()
        {
            InitializeComponent();

            Person person = new Person();
            person.Name = "Andrew";
            this.btn.DataContext = person;
        }
    }
}

You can quickly create a Silvelright application called TooltipDataBindingTest so you can copy and paste the above code.

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you have to handle loaded event of the control and set the tooltip programatically

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I think you need to set DataContext property of TextBlock.

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Sincerely,
Sergey Lutay

 Thank you Sergey.

  Indeed, setting the DataContext on the TextBlock make the tooltip to work:

       <Button x:Name="btn" Content="Caption" Width="100" Height="30">
            <ToolTipService.ToolTip>
                <TextBlock x:Name="txtBlock" Text="{Binding Name}"/>
            </ToolTipService.ToolTip>
        </Button>

But I still don't understand and I am confused.

 Why when using ToolTipService.ToolTip attached property it DOES work:

<UserControl x:Class="TooltipDataBindingTest.Page"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Width="400" Height="300">
    <Grid x:Name="LayoutRoot" Background="White">
        <Button x:Name="btn" Content="Caption" Width="100" Height="30" ToolTipService.ToolTip="{Binding Name}" />
    </Grid>
</UserControl>

but when using a custom layout it does NOT work:

<UserControl x:Class="TooltipDataBindingTest.Page"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Width="400" Height="300">
    <Grid x:Name="LayoutRoot" Background="White">
        <Button x:Name="btn" Content="Caption" Width="100" Height="30">
            <ToolTipService.ToolTip>
                <TextBlock Text="{Binding Name}" />
            </ToolTipService.ToolTip>
        </Button>
    </Grid>
</UserControl>

Both of them use the same way of data binding:

    public partial class Page : UserControl
    {
        public Page()
        {
            InitializeComponent();

            Person person = new Person();
            person.Name = "Andrew";
            this.btn.DataContext = person;
        }
    }

I expect either both to work or not work in the same time. Why they are working differently ?

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 I realize now that the fact that it doesn't work with custom layout has a great impact.

For example, I have a ListBox with ItemSource set.

In order for me to make the tooltip to work with a custom layout like above, what should I do, iterate through all items and set the DataContext for each tooltip TextBlock of an item ?

Again, I don't understand why using attached property works but not when setting a custom layout with ToolTip.Content.

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 anyone ?

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 would be nice to have an explanation

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 anybody :)

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Hi silverbyte,

We have a debug on our labs, and found that the TextBlock's DataContext is null in ToolTipService.ToolTip .  That's why the button's tooltip is empty.

You can try to set the Textblock's datacontext in the code, like below code, the tooltip works fine on our local.

<Button x:Name="btn" Content="My Button" Width="100" Height="25" Click="btn_Click" >
            <ToolTipService.ToolTip>
                    <TextBlock x:Name="txt" Foreground="Red" Text="{Binding name}" Loaded="txt_Loaded"></TextBlock>
            </ToolTipService.ToolTip>
        </Button>

The code:

 private void txt_Loaded(object sender, RoutedEventArgs e)
        {
           TextBlock text = (TextBlock)sender;
            text.DataContext = this.btn.DataContext;
        }

Amanda Wang
Microsoft Online Community Support

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Unfortunately, the approach above does not seem to work when the TextBlock in question is inside a ControlTemplate.  (In my case, the ControlTemplate for a BarDataPoint.)  The Loaded event is never fired.  Can anyone suggest a suitable workaround?   Essentially, how can I get to a TextBlock defined in a ControlTemplate?