MainWindow.xaml

<Window x:Class="MouseMenu.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" 
        Loaded="Window_Loaded" WindowStyle="None" 
        AllowsTransparency="True" ResizeMode="NoResize" ShowInTaskbar="False" ShowActivated="False" Topmost="True"
        Background="Transparent" SizeToContent="WidthAndHeight">


    <Border Padding="6" CornerRadius="12" Background="CornflowerBlue" Margin="20">

        <Border.Effect>
            <DropShadowEffect ShadowDepth="8" BlurRadius="20" Opacity="0.5" />
        </Border.Effect>

        <Grid>

            <StackPanel>
                <Button Content="Option 1" Click="Button_Click" />
                <Button Content="Option 3" Click="Button_Click" />
                <Button Content="Option 4" Click="Button_Click" />
                <Button Content="Option 5" Click="Button_Click" />
            </StackPanel>

        </Grid>

    </Border>
</Window>