StackPanel arranges its elements into a single line that can be oriented horizontally or vertically.
Example:
XAML
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<StackPanel>
<Button Content="Button" Margin="0,0,385,0"/>
<ComboBox Margin="0,0,211,0"/>
<Label Content="Label"/>
<TextBox Height="65" TextWrapping="Wrap" Text="TextBox"/>
</StackPanel>
</Window>