problem with wpf datagrid selection + expander

Question

I have an expander containing a datagrid with a rowdetailstemplate.

When I click on a datagrid row to see the row details template, the expander closes!

Anyone know why and how to fix this?

Update

Turns out that something else is happening:

The expanders are all contained in a TabItem. When I click on the grid row, TabControls.SelectionChanged fires (WHY!!!?!?!!?!?!?!) and then the data is recalculated and rebound.

So the real question is why does click a DataGrid row cause the Parent TabControl's SelectionChanged Event to fire? Here's the XAML:

<Window xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"  x:Class="BPPDemo.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:BPPDemo"
    Title="BPP Demo" Height="600" Width="700" Loaded="Window_Loaded">

<Window.Resources>
    <local:AddrStatusColorConverter x:Key="addressStatusColorConverter"/>

    <local:BoolToVisConverter x:Key="boolToVisConverter"/>
</Window.Resources>

<DockPanel>
    <Menu DockPanel.Dock="Top">
        <Menu.Items>
            <MenuItem Header="File">
                <MenuItem Header="Open Assessment" Command="{Binding SelectAssessmentCommand}"></MenuItem>
                <MenuItem Header="Import Properties" Command="{Binding ImportPropertiesCommand}"></MenuItem>
            </MenuItem>
            <MenuItem Header="Properties" Visibility="{Binding IsSelected, ElementName=tabProperties,Converter={StaticResource boolToVisConverter}}">
                <MenuItem Header="Delete All Properties" Command="{Binding DeleteAllPropertiesCommand}"></MenuItem>
                <MenuItem Header="Resolve Invalid Addresses" Command="{Binding ValidateAddressesCommand}"></MenuItem>
                <MenuItem Header="Select Situs" Command="{Binding SelectSitusCommand}"/>
            </MenuItem>
        </Menu.Items>
    </Menu>

    <DockPanel Margin="10">
        <TextBlock Text="{Binding Assessment.Name}" FontWeight="Normal" FontSize="24" Foreground="#FF5C9EB7" DockPanel.Dock="Top" Margin="0,0,0,10"/>
        <TabControl SelectionChanged="TabControl_SelectionChanged">
            <TabItem x:Name="tabProperties" Header="Properties">
                <DataGrid ItemsSource="{Binding Properties}" AutoGenerateColumns="False" IsReadOnly="True" SelectedItem="{Binding SelectedProperty,Mode=TwoWay}">
                    <DataGrid.Columns>
                        <DataGridTextColumn Header="Description" Binding="{Binding Description}"/>
                        <DataGridTextColumn Header="Cost" Binding="{Binding Cost,StringFormat='{}{0:c}'}"/>
                        <DataGridTextColumn Header="Year Acquired" Binding="{Binding YearAcquired}"/>
                        <DataGridTextColumn Header="Life In Years" Binding="{Binding LifeInYears}"/>
                        <DataGridTextColumn Header="Schedule" Binding="{Binding Schedule}"/>
                        <DataGridTextColumn Header="Current Value" Binding="{Binding CurrentValue,StringFormat='{}{0:c}'}" />
                        <DataGridTextColumn Header="Tax" Binding="{Binding Tax,StringFormat='{}{0:c}'}" />

                        <DataGridTemplateColumn Header="Address">
                            <DataGridTemplateColumn.CellTemplate>
                                <DataTemplate>
                                    <TextBlock Text="{Binding Address}" Foreground="{Binding AddressStatus, Converter={StaticResource addressStatusColorConverter}}"/>
                                </DataTemplate>
                            </DataGridTemplateColumn.CellTemplate>
                        </DataGridTemplateColumn>
                        <DataGridTextColumn Header="Address Status" Binding="{Binding AddressStatus}"/>
                        <DataGridTextColumn Header="Situs" Binding="{Binding Situs}"/>
                    </DataGrid.Columns>

                    <DataGrid.RowDetailsTemplate>
                        <DataTemplate>
                            <TextBlock>THIS ONE WORKS! WHY DOESN'T THE OTHER ONE????</TextBlock>
                        </DataTemplate>
                    </DataGrid.RowDetailsTemplate>


                </DataGrid>
            </TabItem>
            <TabItem Header="Listings" Name="tabListings">

                <DataGrid x:Name="SitusGroups" AutoGenerateColumns="false" SelectionMode="Single" SelectionUnit="FullRow">
                    <DataGrid.Columns>
                        <DataGridTextColumn Header="Situs" Binding="{Binding Situs,StringFormat='{}{0:c}',TargetNullValue='none'}"></DataGridTextColumn>
                        <DataGridTextColumn Header="Cost" Binding="{Binding Cost,StringFormat='{}{0:c}'}"></DataGridTextColumn>
                        <DataGridTextColumn Header="Value" Binding="{Binding Value,StringFormat='{}{0:c}'}"></DataGridTextColumn>
                        <DataGridTextColumn Header="Tax" Binding="{Binding Tax,StringFormat='{}{0:c}'}"></DataGridTextColumn>
                    </DataGrid.Columns>

                    <DataGrid.RowDetailsTemplate>
                        <DataTemplate>
                            <TextBlock>I JUST WANT TO SEE THIS WHEN I CLICK ON A ROW!</TextBlock>
                        </DataTemplate>
                    </DataGrid.RowDetailsTemplate>

                </DataGrid>

               

            </TabItem>
        </TabControl>

    </DockPanel>

</DockPanel>

Ronnie Overby Ronnie Overby · Accepted Answer · 2011-09-18T21:02:15

The problem has to do with the way events are routed. TabControl and DataGrid derive from the same class, so when DataGrid SelectionChanged, my TabControl SelectionChanged handler was firing.

As the last comment at http://www.trentfguidry.net/post/2009/06/13/WPF-TabControl-SelectionChanged.aspx suggests, I checked the original source in my event handler and returned if the reference wasn't my tabcontrol.

problem with wpf datagrid selection + expander

Update

1 Answers