Is Grid.RowSpan ignored when measuring heights of rows? (WPF)

Question

Here is a 2x2 grid, in which the first column spans both rows, but its fixed-height content seems to be dictating the minimum height for the first row:

<UserControl x:Class="Test"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  Width="300">
  <Grid>
    <Grid.ColumnDefinitions>
      <ColumnDefinition Width="Auto" />
      <ColumnDefinition Width="*" />
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
      <RowDefinition Height="*"/>
      <RowDefinition Height="Auto"/>
    </Grid.RowDefinitions>

    <Rectangle Grid.Row="0" Grid.Column="0" Grid.RowSpan="2" Fill="Green"
      Width="50" Height="50" VerticalAlignment="Top" />

    <TextBlock Grid.Row="0" Grid.Column="1" Margin="3" TextWrapping="Wrap">
        Some text goes here. 
    </TextBlock>

    <Button Grid.Row="1" Grid.Column="1" HorizontalAlignment="Right">OK</Button>
  </Grid>
</UserControl>

In this example, the first row is always at least 50 high, as is evident from the space consumed by the TextBlock, even though I'd like it (and as a consequence, the entire control) to be shorter if there isn't much text to display. Am I missing something, or is this a WPF layout bug?

(Yes, I know I could easily code it with nested grids, but this is a simplified distillation of a more complicated case.)

Answer 1

What you should be seeing is the Button taking as much height as it needs and the TextBlock getting the rest of the control's available height. Since Column 0 only has the fixed size Rectangle in it, it will always have a width of 50, with Column 1 taking the rest of the available width. Are you seeing something other than that or is there something different that you want the layout to do?