The UniformGrid

<Window x:Class="LayoutPanels.TheUniformGrid"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="TheUniformGrid" Height="320" Width="400">
    <UniformGrid Rows="2" Columns="2">
      <Button>Top Left</Button>
      <Button>Top Right</Button>
      <Button>Bottom Left</Button>
      <Button>Bottom Right</Button>
    </UniformGrid>
</Window>

