<Style TargetType="{x:Type Window}">

        <Setter Property="WindowStyle" Value="None"/>

        <Setter Property="ResizeMode" Value="CanResize"/>

        <Setter Property="WindowChrome.WindowChrome">

            <Setter.Value>

                <WindowChrome CaptionHeight="0" ResizeBorderThickness="5"/>

            </Setter.Value>

        </Setter>

</Style>

protected override CreateParams CreateParams

{

    get

    {

        CreateParams cp = base.CreateParams;

        cp.Style &= ~0xC00000;

        return cp;

    }

}