window not coming proper

Question

My window is not coming of proper size.

 

<Window x:Class="xxx.WPopup"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Height="152" Width="494" ResizeMode="NoResize" WindowStyle="ToolWindow">
    <Grid>
        <Button x:Name="MyButton" Content="MY" HorizontalAlignment="Center" Margin="206,88,206,19" VerticalAlignment="Center" Width="76" Click="okButton_Click"/>
        <Label x:Name="messageLabel" Content="" HorizontalAlignment="Center" Margin="225,35,225,68" VerticalAlignment="Center"/>
    </Grid>
</Window>