I'm not too familiar with wpf layout-system. so i'm ready to start and understanding that. at the first of road i have a problem with wpf. so according to below markup, i have 4 button which when we run project everything is true.
<Window ... WindowStartupLocation="CenterOwner" SizeToContent="WidthAndHeight" Name="wMessage" ShowInTaskbar="False" ResizeMode="NoResize" WindowStyle="SingleBorderWindow">
<WrapPanel Orientation="Horizontal">
<Button Content="Button 1" Margin="10" />
<Button Content="Button 2" Margin="10" />
<Button Content="Button 3" Margin="10" />
<Button Content="Button 4" Margin="10" />
</WrapPanel>
at the right side and bottom of window something appears like a border which i don't know this comes from where!!!