ProgressWindow.xaml

<Window
    x:Class="SheetReader.Wpf.Test.ProgressWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    Title="Progress"
    Closing="OnClosing"
    ResizeMode="NoResize"
    SizeToContent="WidthAndHeight"
    WindowStartupLocation="CenterOwner"
    mc:Ignorable="d">
    <StackPanel MinWidth="300" Orientation="Vertical">
        <ProgressBar
            x:Name="pg"
            Height="23"
            Margin="10,10,10,0"
            HorizontalAlignment="Stretch"
            VerticalAlignment="Top"
            IsIndeterminate="True" />
        <Label
            x:Name="lbl"
            Margin="10,5,10,0"
            HorizontalAlignment="Stretch"
            VerticalAlignment="Top"
            HorizontalContentAlignment="Center"
            Content="..."
            TextBlock.TextAlignment="Center" />
        <Button
            Width="75"
            Height="23"
            Margin="0,5,10,10"
            HorizontalAlignment="Right"
            VerticalAlignment="Bottom"
            Content="Cancel"
            IsCancel="True" />
    </StackPanel>
</Window>