Flow.Launcher/Flow.Launcher/MsgWithButton.xaml

<Window
    x:Class="Flow.Launcher.MsgWithButton"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Msg"
    Width="420"
    Height="60"
    Background="#ebebeb"
    ResizeMode="NoResize"
    ShowInTaskbar="False"
    SizeToContent="Height"
    Topmost="True"
    WindowStyle="None">
    <Window.Triggers>
        <EventTrigger RoutedEvent="Window.Loaded">
            <BeginStoryboard>
                <Storyboard>
                    <DoubleAnimation
                        x:Name="showAnimation"
                        AccelerationRatio="0.2"
                        Storyboard.TargetProperty="Top"
                        Duration="0:0:0.3" />
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
    </Window.Triggers>

    <StackPanel Orientation="Vertical">
        <Grid
            Margin="5"
            HorizontalAlignment="Stretch"
            VerticalAlignment="Stretch">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="32" />
                <ColumnDefinition />
                <ColumnDefinition Width="2.852" />
                <ColumnDefinition Width="13.148" />
            </Grid.ColumnDefinitions>
            <Image
                x:Name="imgIco"
                Width="32"
                Height="32"
                Margin="0 9"
                HorizontalAlignment="Left" />
            <Grid
                Grid.Column="1"
                Margin="5 0 0 0"
                HorizontalAlignment="Stretch"
                VerticalAlignment="Stretch">
                <Grid.RowDefinitions>
                    <RowDefinition />
                    <RowDefinition />
                </Grid.RowDefinitions>
                <TextBlock
                    x:Name="tbTitle"
                    FontSize="16"
                    FontWeight="Medium"
                    Foreground="#37392c">
                    Title
                </TextBlock>
                <TextBlock
                    x:Name="tbSubTitle"
                    Grid.Row="1"
                    Foreground="#8e94a4">
                    sdfdsf
                </TextBlock>
            </Grid>
            <Image
                x:Name="imgClose"
                Grid.Column="2"
                Grid.ColumnSpan="2"
                Width="16"
                HorizontalAlignment="Right"
                VerticalAlignment="Top"
                Cursor="Hand" />
        </Grid>
        <Button
            x:Name="btn"
            Margin="5 0 5 5"
            HorizontalAlignment="Stretch"
            Content="fwafaw"
            Foreground="#dcdcdc" />
    </StackPanel>
</Window>