Question

In the below XAML, the combobox is not visible. What am I doing wrong?

<Grid>
  <StackPanel>
    <ComboBox Name="combo1"
              ItemsSource="{Binding}"
              DisplayMemberPath="PartNumber" />
  </StackPanel>
  <Grid>
    <Grid.RowDefinitions>
      <RowDefinition></RowDefinition>
      <RowDefinition></RowDefinition>
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
      <ColumnDefinition></ColumnDefinition>
      <ColumnDefinition></ColumnDefinition>
    </Grid.ColumnDefinitions>

    <TextBlock Grid.Row="0"
               Grid.Column="0"
               Text="{Binding ElementName=combo1, Path=SelectedItem.PartName}"
               Background="AliceBlue" />
    <TextBlock Grid.Row="0"
               Grid.Column="1"
               Text="{Binding ElementName=combo1, Path=SelectedItem.PartQuantity}"
               Background="Beige" />
  </Grid>
</Grid>

Answer 1

You have placed the grid above the combo box which causes the problem , you can either put a new row for the combo or use a canvas for specify the zIndex. Please checkout the xaml part below.

<Canvas>
  <ComboBox Canvas.ZIndex="2"
            Width="300"
            Name="combo1"
            ItemsSource="{Binding}"
            DisplayMemberPath="PartNumber" />

  <Grid>
    <Grid.RowDefinitions>
      <RowDefinition></RowDefinition>
      <RowDefinition></RowDefinition>
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
      <ColumnDefinition></ColumnDefinition>
      <ColumnDefinition></ColumnDefinition>
    </Grid.ColumnDefinitions>

    <TextBlock Grid.Row="0"
               Grid.Column="0"
               Text="{Binding ElementName=combo1, Path=SelectedItem.PartName}"
               Background="AliceBlue" />
    <TextBlock Grid.Row="0"
               Grid.Column="1"
               Text="{Binding ElementName=combo1, Path=SelectedItem.PartQuantity}"
               Background="Beige" />
  </Grid>
</Canvas>