WPF ToolTip does not update

user_701485 0
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Assuming I have a simple class that represents a staff member

class Staff
{
    public string FirstName { get; set; }
    public string FamilyName { get; set; }
    public int SecondsAlive { get; set; }        
}

and I have a DataTemplate for staff

<DataTemplate DataType={x:Type Staff}>
    <StackPanel Orientation="Horizontal">
        <TextBlock Text={Binding FirstName}/>
        <TextBlock Text=" ">
        <TextBlock Text={Binding FamilyName}/>
        <StackPanel.ToolTip>
            <TextBlock Text={Binding SecondsAlive}/>
        </StackPanel.ToolTip>
     </StackPanel>
</DataTemplate>

I then show a whole bunch of staff in a ListBox

myListBox.ItemsSource = GetAllStaff();

Pretty standard stuff. The problem I have is that the tooltip which shows the number of seconds that someone has been alive does not get updated. When you first mouse over a staff member then it works fine but from then on it keeps that value for ever. I could implement INotifyPropertyChanged to get around this but it seems like overkill to do this for every staff member whenever SecondsAlive changes. Say I have 400 staff in the list then I have to raise 400 events even though the user might never look at another tooltip. What I would like is to make the tooltip request the SecondsAlive property ever time it is shown. Is that possible?

Please note that this is just an example and I don't need to know how many seconds my staff have been alive :-) But I have the same issue that I need to raise an even around 400 times just for a tooltip which someone probably won't look at.

binding wpf .net c#
6 Answers

Although this is an old question.

In this case:

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

The ToolTip control is hosted by an isolate HWND (a.k.a, a native window). It should have its own DataContext, the correct binding expresion should be like:

    <StackPanel.ToolTip>
        <ToolTip 
            DataContext="{Binding PlacementTarget.DataContext, RelativeSource={RelativeSource Self}}">
            <TextBlock Text="{Binding SecondsAlive}"/>
        </ToolTip>
    </StackPanel.ToolTip>
user_86245260

I was having the same problem of it not updating. I found the solution to be adding the controls to a ToolTip template:

<DataTemplate DataType={x:Type Staff}>
    <StackPanel Orientation="Horizontal">
        <TextBlock Text={Binding FirstName}/>
        <TextBlock Text=" ">
        <TextBlock Text={Binding FamilyName}/>
        <StackPanel.ToolTip>
            <Tooltip>
                <ToolTip.Template>
                    <ControlTemlate>
                        <TextBlock Text={Binding SecondsAlive}/>
                    </ControlTemplate>
                </ToolTip.Template>
            </Tooltip> 
        </StackPanel.ToolTip>
     </StackPanel>
</DataTemplate>

I don't quite understand why this is needed or why this makes it behave differently but it fixed the problem.

user_146552060
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