<Window x:Class="AAA.MyForm"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:cdp="clr-namespace:AAA"
mc:Ignorable="d"

ShowInTaskbar="False"
SizeToContent="WidthAndHeight"
WindowStartupLocation="CenterOwner" 
...					
Background="Red"
>