xaml and C# should be equivalent, but they're not

Question

I have created a one-row grid in xaml, and then add rows dynamically in C#. Yet, although they ALMOST line up, they don't QUITE do so. Why would this be, when the code is the same?

The most pertinent part of the XAML is:

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*" />
        <ColumnDefinition Width="*" />
        <ColumnDefinition Width="*" />
        <ColumnDefinition Width="4*" />
        <ColumnDefinition Width="*" />
        <ColumnDefinition Width="3*" />
        <ColumnDefinition Width="2*" />
        <ColumnDefinition Width="2*" />
    </Grid.ColumnDefinitions>

The most pertinent part of the C# is:

Grid grd = new Grid();
ColumnDefinition c0 = new ColumnDefinition(); 
c0.Width = new GridLength(1, GridUnitType.Star); 
ColumnDefinition c1 = new ColumnDefinition(); 
c1.Width = new GridLength(1, GridUnitType.Star); 
ColumnDefinition c2 = new ColumnDefinition(); 
c2.Width = new GridLength(1, GridUnitType.Star);
ColumnDefinition c3 = new ColumnDefinition();
c3.Width = new GridLength(4, GridUnitType.Star);
ColumnDefinition c4 = new ColumnDefinition();
c4.Width = new GridLength(1, GridUnitType.Star);
ColumnDefinition c5 = new ColumnDefinition();
c5.Width = new GridLength(3, GridUnitType.Star);
ColumnDefinition c6 = new ColumnDefinition();
c6.Width = new GridLength(2, GridUnitType.Star);
ColumnDefinition c7 = new ColumnDefinition();
c7.Width = new GridLength(2, GridUnitType.Star);
grd.ColumnDefinitions.Add(c0);
grd.ColumnDefinitions.Add(c1);
grd.ColumnDefinitions.Add(c2);
grd.ColumnDefinitions.Add(c3);
grd.ColumnDefinitions.Add(c4);
grd.ColumnDefinitions.Add(c5);
grd.ColumnDefinitions.Add(c6);
grd.ColumnDefinitions.Add(c7);
// Add it to the StackPanel
spNufan.Children.Add(grd);

Screenshot http://getfile6.posterous.com/getfile/files.posterous.com/temp-2012-02-16/EHnCudinikxcfprHxjywowEcwBssAcpbdchkeinAqJdhvuwDIhJxoonrjGEq/MisalignedColumns.bmp.scaled1000.jpg

Updated

It seems I have to choose between having all my columns line up and having a really wide form OR allowing "cells" to wrap with wiggly/wavy column alignment.

At first I had wrapping working fine, but the columns weren't exactly aligned, but now that I've added the following (SharedSizeGroup element) to my xaml:

<StackPanel x:Name="spNufan" Grid.IsSharedSizeScope="True"
        Orientation="Vertical">
<Grid ShowGridLines="True" >
    <Grid.ColumnDefinitions>
        <ColumnDefinition SharedSizeGroup="ZeroethColumn" Width="*" />
        <ColumnDefinition SharedSizeGroup="FirstColumn" Width="*" />
        <ColumnDefinition SharedSizeGroup="SecondColumn" Width="*" />
        <ColumnDefinition SharedSizeGroup="ThirdColumn" Width="4*" />
        <ColumnDefinition SharedSizeGroup="FourthColumn" Width="*" />
        <ColumnDefinition SharedSizeGroup="FifthColumn" Width="3*" />
        <ColumnDefinition SharedSizeGroup="SixthColumn" Width="2*" />
        <ColumnDefinition SharedSizeGroup="SeventhColumn" Width="2*" />
    </Grid.ColumnDefinitions>
    <TextBlock Grid.Column="0"
               Margin="2"
               TextAlignment="Left"
               TextWrapping="Wrap"
               . . .

...it no longer does (allow the cells to wrap as they should), although I have TextWrapping set to "Wrap"

Here is my pertinent C#:

Grid grd = new Grid();
grd.ShowGridLines = true;
ColumnDefinition c0 = new ColumnDefinition(); 
c0.Width = new GridLength(1, GridUnitType.Star);
c0.SharedSizeGroup = "ZeroethColumn";
. . .
spNufan.Children.Add(grd);
. . .
TextBlock tbDateTime = new TextBlock();
tbDateTime.Margin = _margin;
tbDateTime.Background = scb;
tbDateTime.TextWrapping = TextWrapping.Wrap;
tbDateTime.TextAlignment = TextAlignment.Left;
tbDateTime.VerticalAlignment = VerticalAlignment.Center;
tbDateTime.Text = ADateTime.ToString();
Grid.SetColumn(tbDateTime, LogParsePumpViewerConsts.GRID_COL_DATETIME);
grd.Children.Add(tbDateTime);

Answer 1

You have different content in the orange group as compared to the red group. The text overflow will make the column sizes slightly different. Most notably in the first column, 2/12/2012 is larger than 2/8/2012.