SearchDialog.xaml

<ContentDialog
    x:Class="NGopher.SearchDialog"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:NGopher"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    x:Uid="SearchDialog"
    Title="SEARCH"
    PrimaryButtonText="search"  
    SecondaryButtonText="cancel"
    PrimaryButtonClick="ContentDialog_PrimaryButtonClick"
    SecondaryButtonClick="ContentDialog_SecondaryButtonClick">

    <StackPanel VerticalAlignment="Stretch" HorizontalAlignment="Stretch">
        <!-- Content body -->
        <TextBlock Name="InfoTextBlock" Style="{StaticResource MessageDialogContentStyle}" 
                   TextWrapping="Wrap" />
        <TextBox x:Uid="SearchTextBox" Name="SearchTextBox" Header="Search string"/>
    </StackPanel>
</ContentDialog>