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GridSplitter acts differently when moved to external resource (UserControl)

Since my WPF application uses GridSplitters on several occasions, I want to extract that XAML snippet into a separate UserControl.
Of course, using a ResourceDictionary would be nicer. But that way, I can only define a ControlTemplate for the splitter's content and use it within the Template-attribute afterwards - which removes the ability to define all those GridSplitter attributes only once and then consecutively use them.
The GridSplitter UserControl, GridSplitter.xaml:
<GridSplitter HorizontalAlignment="Stretch" Margin="3" ResizeBehavior="PreviousAndNext"
ResizeDirection="Columns" VerticalAlignment="Stretch">
<GridSplitter.Template>
<ControlTemplate TargetType="{x:Type GridSplitter}">
<Grid>
<Button Content="⁞" />
<Rectangle Fill="#00FFFFFF" />
</Grid>
</ControlTemplate>
</GridSplitter.Template>
</GridSplitter>
The usage in MainWindow.xaml:
<Window
(...)
xmlns:uc="clr-namespace:Yoda.Frontend.Resources"
(...)>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition MinWidth="100" Width="200" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition MinWidth="400" Width="*" />
</Grid.ColumnDefinitions>
<!-- (...) -->
<uc:GridSplitter Grid.Column="1" />
<!-- (...) -->
</Grid>
<!-- (...) -->
</Window>
The result of using the above code is a splitter which can't be moved in any direction.
However, using the ResourceDictionary dictionary approach mentioned above, I get a movable GridSplitter.
But despite working perfectly directly in MainWindow.xaml, it only resizes the third grid column.
Sure, setting Width isn't recommended when using GridSplitter. But why does it work whenever the splitter is defined within the main window and only fails to do so when used as an UserControl? And how to fix that in an MVVM, no code-behind way?

In case you only what to have a nice looking splitter, you can use this code:
<Grid.ColumnDefinitions>
<ColumnDefinition MinWidth="100" Width="Auto" />
<ColumnDefinition MinWidth="20" Width="Auto" />
<ColumnDefinition MinWidth="400" Width="Auto" />
</Grid.ColumnDefinitions>
<!-- (...) -->
<GridSplitter Grid.Column="1" Background="Gray" HorizontalAlignment="Stretch"
VerticalAlignment="Stretch" />
<TextBlock Text="⁞" Grid.Column="1" HorizontalAlignment="Center" VerticalAlignment="Center"
IsHitTestVisible="False" />
<!-- (...) -->
Another solution would be to define the ControlTemplate as a resource and then use that for the GridSplitter:
<Window.Resources>
<ControlTemplate TargetType="{x:Type GridSplitter}" x:Key="gridSplitter">
<Grid Background="Transparent">
<Button Content="⁞" IsHitTestVisible="False" />
<Rectangle Fill="#00FFFFFF" IsHitTestVisible="False" />
</Grid>
</ControlTemplate>
</Window.Resources>
<Grid>
<Grid HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Background="Blue">
<Grid.ColumnDefinitions>
<ColumnDefinition MinWidth="100" Width="Auto" />
<ColumnDefinition MinWidth="20" Width="Auto" />
<ColumnDefinition MinWidth="400" Width="Auto" />
</Grid.ColumnDefinitions>
<!-- (...) -->
<GridSplitter Grid.Column="1" Template="{StaticResource gridSplitter}" />
<!-- (...) -->
</Grid>
<!-- (...) -->
</Grid>
There's also a solution if you really want to use the set properties within the splitter template: use a style to add those. It would look like this:
<Window.Resources>
<ControlTemplate TargetType="{x:Type GridSplitter}" x:Key="gridSplitter">
<Grid Background="Transparent">
<Button Content="⁞" IsHitTestVisible="False"/>
<Rectangle Fill="#00FFFFFF" IsHitTestVisible="False"/>
</Grid>
</ControlTemplate>
<Style TargetType="{x:Type GridSplitter}" x:Key="styleGridSplitter">
<Setter Property="Template" Value="{StaticResource gridSplitter}" />
<Setter Property="ResizeBehavior" Value="PreviousAndNext" />
<Setter Property="ResizeDirection" Value="Columns" />
<Setter Property="VerticalAlignment" Value="Stretch" />
<Setter Property="HorizontalAlignment" Value="Stretch" />
<Setter Property="Margin" Value="3" />
</Style>
</Window.Resources>
<Grid>
<Grid HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Background="Blue">
<Grid.ColumnDefinitions>
<ColumnDefinition MinWidth="100" Width="Auto" />
<ColumnDefinition MinWidth="20" Width="Auto" />
<ColumnDefinition MinWidth="400" Width="Auto" />
</Grid.ColumnDefinitions>
<!-- (...) -->
<GridSplitter Grid.Column="1" Style="{StaticResource styleGridSplitter}"/>
<!-- (...) -->
</Grid>
<!-- (...) -->
</Grid>

Grid - Hiding row and textblock display issue

I have a simple dialog - A Grid with 4 TextBlock's wherein I bind the visibility of the 2nd and 3rd TextBlock to a property but it doesn't work as expected i.e., the conditional message appears truncated when viewing the dialog. The 2 variants of the dialog are as below:
Some Text
Conditional Message 1
B C
or
Some Text
Conditional Message 2
B C
The XAML of the dialog is as attached below.
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:cl="http://www.caliburnproject.org"
xmlns:local="clr-namespace:ABC.DrillDown"
xmlns:iwpf="clr-namespace:ABC.Mvvm.Wpf;assembly=ABC.Mvvm.Wpf"
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" x:Class="ABC.DrillDown.Views.MessageView"
Title="{Binding WindowTitle}" WindowStartupLocation="CenterScreen" MaxWidth="525" MinWidth="525" Background="White" MinHeight="275" MaxHeight="275">
<Window.Resources>
<iwpf:BoolToVisibilityConverter x:Key="booleanToVisibilityConverter"/>
</Window.Resources>
<Grid Margin="0,0,0,0" VerticalAlignment="Top" HorizontalAlignment="Left" Width="514" >
<Grid.RowDefinitions>
<RowDefinition Height="Auto" MinHeight="64"/>
<RowDefinition Height="{Binding TransactionsModified, Converter={StaticResource booleanToVisibilityConverter}}">
<RowDefinition.Style>
<Style TargetType="{x:Type RowDefinition}">
<Setter Property="Height" Value="Auto" />
<Style.Triggers>
<!--Hide Row-1-->
<DataTrigger Binding="{Binding TransactionsModified}" Value="False">
<Setter Property="Height" Value="0" />
</DataTrigger>
</Style.Triggers>
</Style>
</RowDefinition.Style>
</RowDefinition>
<RowDefinition Height="{Binding TransactionsDeleted, Converter={StaticResource booleanToVisibilityConverter}}">
<RowDefinition.Style>
<Style TargetType="{x:Type RowDefinition}">
<Setter Property="Height" Value="Auto" />
<Style.Triggers>
<!--Hide Row-2-->
<DataTrigger Binding="{Binding TransactionsDeleted}" Value="false">
<Setter Property="Height" Value="0" />
</DataTrigger>
</Style.Triggers>
</Style>
</RowDefinition.Style>
</RowDefinition>
<RowDefinition Height="Auto" MinHeight="80"/>
<RowDefinition Height="Auto" MinHeight="30"/>
<RowDefinition Height="Auto" MinHeight="12"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<TextBlock Grid.Row="0" Grid.Column="0" TextWrapping="NoWrap" HorizontalAlignment="Left" xml:space="preserve" VerticalAlignment="Top" Height="64" Width="478">Some Text </TextBlock>
<TextBlock Grid.Row="1" Grid.Column="0" Text="{Binding TransactionsModified}" Visibility="{Binding TransactionsModified, Converter={StaticResource booleanToVisibilityConverter}}" TextWrapping="NoWrap" HorizontalAlignment="Left" xml:space="preserve" Width="0" >
Conditional Text - 1
</TextBlock>
<TextBlock Grid.Row="2" Grid.Column="0" Text="{Binding TransactionsDeleted}" Visibility="{Binding TransactionsDeleted, Converter={StaticResource booleanToVisibilityConverter}}" TextWrapping="NoWrap" HorizontalAlignment="Left" xml:space="preserve" Width="0">
Conditional Text - 2
</TextBlock>
<TextBlock Grid.Row="3" Grid.Column="0" TextWrapping="NoWrap" HorizontalAlignment="Left" xml:space="preserve" Width="425">
Text 3
Text 4
</TextBlock>
</Grid>
</Window>
C

You have a couple of RowDefinition where there is a wrong Height (you should remove this part)
Height="{Binding TransactionsModified, Converter={StaticResource booleanToVisibilityConverter}}">
Of course binding Height directly to a bool makes no sense: you already have the more reasonable triggers in the following part (they look fine at first sight)

3x3 Grid containing a Path in the center fills the entire grid

I have the following ControlTemplate that I am using in an ItemsControl. It is essentially a 3x3 Grid with a Path in the center and a Textbox/Textblock on top of it. When I use this, the Path takes up all of the space within the ItemsControl, and ignores the column/row definition constraints. Can anyone tell me why this is happening? I tried wrapping the Path in a Canvas but that didn't seem to help.
Thanks!
<controls:Toolbox x:Key="DrawingShapeTemplates"
DefaultItemSize="60, 60"
SnapsToDevicePixels="True"
ScrollViewer.HorizontalScrollBarVisibility="Disabled">
<ItemsControl.Items>
<Path Style="{StaticResource Square}"
ToolTip="Square Shape">
<controls:DesignerItem.MoveThumbTemplate>
<ControlTemplate>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="1*" />
<RowDefinition Height="3*" />
<RowDefinition Height="1*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*" />
<ColumnDefinition Width="3*" />
<ColumnDefinition Width="1*" />
</Grid.ColumnDefinitions>
<StackPanel Grid.Column="1">
<TextBlock Text="Length" />
<TextBox MinWidth="{Binding RelativeSource={RelativeSource AncestorType=controls:DesignerItem}, Path=ActualWidth}" />
</StackPanel>
<Canvas Grid.Column="1"
Grid.Row="1">
<Path Style="{StaticResource Square_DragThumb}" />
</Canvas>
</Grid>
</ControlTemplate>
</controls:DesignerItem.MoveThumbTemplate>
</Path>
</ItemsControl.Items>
</controls:Toolbox>
The Style.
<Style x:Key="Square"
TargetType="Path"
BasedOn="{StaticResource StandardShapeStyle}">
<Setter Property="Data">
<Setter.Value>
<RectangleGeometry Rect="50 50 50 50" />
</Setter.Value>
</Setter>
</Style>
<Style x:Key="Square_DragThumb"
TargetType="Path"
BasedOn="{StaticResource Square}">
<Setter Property="IsHitTestVisible"
Value="True" />
<Setter Property="Fill"
Value="Transparent" />
<Setter Property="Stroke"
Value="Transparent" />
</Style>
Edit
The source for this was downloaded from hereenter link description here. If you replace the <Path Style="{StaticResource Decision}" at line 469 with the following, you will get the same result that I do.
<Path Style="{StaticResource Decision}"
ToolTip="Decision">
<s:DesignerItem.MoveThumbTemplate>
<ControlTemplate>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="1*" />
<RowDefinition Height="3*" />
<RowDefinition Height="1*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="1*" />
<ColumnDefinition Width="3*" />
<ColumnDefinition Width="1*" />
</Grid.ColumnDefinitions>
<StackPanel Grid.Column="1">
<TextBlock Text="Length" />
<TextBox MinWidth="{Binding RelativeSource={RelativeSource AncestorType=s:DesignerItem}, Path=ActualWidth}" />
</StackPanel>
<Path Grid.Column="1"
Grid.Row="1"
Style="{StaticResource Decision_DragThumb}" />
</Grid>
</ControlTemplate>
</s:DesignerItem.MoveThumbTemplate>
</Path>
The following are pictures of what I am trying to accomplish and what the actual result is. I want to display a label and a text box on all four sides of the selected item when it is selected. Ultimately the label/textbox visibility will be databound to the DesignerItem.IsSelected dependency property, but that hasn't been wired up yet.
Expected result:
Actual result:

Typically Canvas do to clip it's children by default so you need to set it explicitly as ClipToBounds="True"
eg
<Canvas Grid.Column="1"
Grid.Row="1"
ClipToBounds="True">
<Path Style="{StaticResource Square_DragThumb}" />
</Canvas>
Update
Replace the Path element in FlowChartSymbols.xaml at line 469 with the following Grid
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="auto" />
<RowDefinition />
</Grid.RowDefinitions>
<StackPanel Grid.Column="1">
<TextBlock Text="Length" HorizontalAlignment="Center"/>
<TextBox />
<StackPanel.Style>
<Style TargetType="StackPanel">
<Style.Triggers>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource FindAncestor,AncestorType=s:DesignerItem}}"
Value="{x:Null}">
<Setter Property="Visibility" Value="Collapsed"/>
</DataTrigger>
</Style.Triggers>
</Style>
</StackPanel.Style>
</StackPanel>
<Path Style="{StaticResource Decision}"
Grid.Row="1" Grid.Column="1"
ToolTip="Decision">
<s:DesignerItem.MoveThumbTemplate>
<ControlTemplate>
<Path Style="{StaticResource Decision_DragThumb}" />
</ControlTemplate>
</s:DesignerItem.MoveThumbTemplate>
</Path>
</Grid>
this is how you can achieve the same. also fixed toolbox issue by adding a trigger to detect if it is inside a designer item or simply in a toolbox

Margin difference in nested ListBox with DataTemplates

I have a problem with my ListBox. I have written several DataTemplates which I use in a ListBox. Each one of these contains a grid and may contain a nested ListBox depending on the item.
My problem is: The height of these nested ListBoxes seem to be different to the root ListBox's height. Additionally it seems, that there is sometimes one pixel margin to the element above.
Has someone encountered this problem, too and maybe solved it?
XAML-Code:
<!-- Template for SubData-Items -->
<DataTemplate x:Key="DataTemplate">
<Grid x:Name="baseGrid" Grid.Column="0" Grid.ColumnSpan="999" Background="Violet">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="{Binding ElementName=Col0, Path=Width}" />
<ColumnDefinition Width="{Binding ElementName=Col1, Path=Width}" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="{Binding ElementName=Row0, Path=Height}"/>
</Grid.RowDefinitions>
<TextBlock Grid.Column="1" Text="{Binding Bezeichnung}" HorizontalAlignment="Left" VerticalAlignment="Center" FontSize="12" />
<Line Grid.ColumnSpan="999" Stroke="Black" X1="0" X2="{Binding ElementName=baseGrid, Path=ActualWidth, Mode=OneWay}" Y1="0" Y2="0" VerticalAlignment="Bottom" />
</Grid>
</DataTemplate>
<!-- Template for Items -->
<DataTemplate x:Key="GroupDataTemplate">
<Grid Grid.ColumnSpan="999" Background="Blue">
<Grid.RowDefinitions>
<RowDefinition Height="{Binding ElementName=Gantt, Path=GridRowHeight}" />
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid x:Name="baseGrid" Grid.Column="0" Grid.ColumnSpan="999">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="{Binding ElementName=Col0, Path=Width}" />
<ColumnDefinition Width="{Binding ElementName=Col1, Path=Width}" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="{Binding ElementName=Row0, Path=Height}"/>
</Grid.RowDefinitions>
<TextBlock Grid.Column="1" Text="{Binding Bezeichnung}" HorizontalAlignment="Left" VerticalAlignment="Center" FontSize="12" />
</Grid>
<Grid x:Name="expandedGrid" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="999">
<ListBox x:Name="LBMaGruppen" ItemTemplate="{StaticResource DataTemplate}" ItemsSource="{Binding SubdataObjects}"
VerticalAlignment="Stretch" HorizontalAlignment="Stretch" HorizontalContentAlignment="Stretch" Height="Auto" Margin="0,0,2,0"
ScrollViewer.CanContentScroll="false" ScrollViewer.HorizontalScrollBarVisibility="Disabled" ScrollViewer.VerticalScrollBarVisibility="Disabled" BorderThickness="0" />
</Grid>
</Grid>
</DataTemplate>
<!-- Grid with ListBox -->
<Grid>
<Grid.RowDefinitions>
<RowDefinition x:Name="Row0" Height="34"/>
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition x:Name="Col0" Width="25" />
<ColumnDefinition x:Name="Col1" Width="*" />
</Grid.ColumnDefinitions>
<ListBox Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="999" ItemsSource="{Binding ItemSource, Mode=OneWay}"
ItemTemplate="{StaticResource GroupDataTemplate}"
VerticalAlignment="Stretch" HorizontalAlignment="Stretch" Height="Auto"
ScrollViewer.CanContentScroll="true"
ScrollViewer.IsDeferredScrollingEnabled="False"
ScrollViewer.HorizontalScrollBarVisibility="Disabled"
ScrollViewer.VerticalScrollBarVisibility="Disabled"
FontSize="10" />
</Grid>

qqbenq gave a very nice solution . Here is another way to do it.
the control templates of ListBox and ListBoxItem has padding inside their borders. Thankfully ListBoxItem border's padding can be control by a style like so:
<Style
TargetType="ListBoxItem">
<Setter
Property="Padding"
Value="0" />
</Style>
but unfortunately for the ListBox , you will have to override the default template with all of its details to change its internal border's hard-coded padding like this:
<Style
TargetType="ListBox">
<Setter
Property="Template">
<Setter.Value>
<ControlTemplate
TargetType="{x:Type ListBox}">
<Border
x:Name="Bd"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}"
Padding="0"
SnapsToDevicePixels="true">
<ScrollViewer
Focusable="false"
Padding="{TemplateBinding Padding}">
<ItemsPresenter
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
</ScrollViewer>
</Border>
<ControlTemplate.Triggers>
<Trigger
Property="IsEnabled"
Value="false">
<Setter
Property="Background"
TargetName="Bd"
Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}" />
</Trigger>
<Trigger
Property="IsGrouping"
Value="true">
<Setter
Property="ScrollViewer.CanContentScroll"
Value="false" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
One last note : remove the Margin that you added inside your xaml.
Solution complete

Add a Margin="-2,0,0,0" and a Padding="-1" to your "LBMaGruppen" named ListBox.
<ListBox x:Name="LBMaGruppen" ItemTemplate="{StaticResource DataTemplate}" ItemsSource="{Binding SubdataObjects}"
VerticalAlignment="Stretch" HorizontalAlignment="Stretch" HorizontalContentAlignment="Stretch" Height="Auto" Margin="-2,0,0,0" Padding="-1"
ScrollViewer.CanContentScroll="false" ScrollViewer.HorizontalScrollBarVisibility="Disabled" ScrollViewer.VerticalScrollBarVisibility="Disabled" BorderThickness="0" />
Also, the "root" element's height is binded to {Binding ElementName=Gantt, Path=GridRowHeight}, while the "sub" element's height to {Binding ElementName=Row0, Path=Height}, so this must cause the difference.

It seems that you have auto height set on all your ListBox. You could try setting the height to a specific size. EDIT: I see you already have ScrollViewer settings. I think setting the height of the box to a specific size instead of auto will do what you want.
As to the padding between elements see the ListBox.ItemContainerSyle which should allow you to set the margin between elements.

C#, WPF, Autorezise Listbox when window resize

C#, Visual Studio 2010, dot net 4, WPF, Microsoft Ribbon
I have a WPF window with the ribbon menues at the top of the window and an area below
where I try to fill with my controls however I can not get the controls to rezise with
my window.
The listbox in the below example should be fully "expanded" witin its boundaries when the window appear and its width should follow the window width when the user resize the window
(the user should not resize the controls itself) by dragging i nthe windows sides.
I tried a lot of playing around with the controls and searched the web but have not been able to
find a solution (some site indicated the usage of border would do the trick).
The Image image1 is a background image spanning over the whole "surface".
The Image image2 is a small logo picture.
<DockPanel DockPanel.Dock="Top">
<Grid DockPanel.Dock="Top" Height="526" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="2" Name="BaseGrid">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="1" />
<RowDefinition Height="60" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Image Grid.Column="0" Grid.Row="0" Grid.RowSpan="3" HorizontalAlignment="Left" Name="image1" VerticalAlignment="Top" Source="........./el_bg.jpg" Stretch="None" />
<Grid Grid.Column="0" Grid.Row="1" VerticalAlignment="Top" Margin="2" HorizontalAlignment="Left">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="200" />
<ColumnDefinition Width="100" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="50" />
</Grid.RowDefinitions>
<Image Grid.Column="0" Grid.Row="0" HorizontalAlignment="Left" Name="image2" Stretch="Fill" VerticalAlignment="Top" Source="........./shiny_rgb.png" />
<ListBox Grid.Column="2" Grid.Row="0" Name="MessageToUser" VerticalAlignment="Top" />
</Grid>
</Grid>
</DockPanel>
Regards

You're setting horizontal alignments to Left that shouldn't be set. Try this:
<DockPanel DockPanel.Dock="Top">
<Grid DockPanel.Dock="Top" Height="526" VerticalAlignment="Top" Margin="2" Name="BaseGrid">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="1" />
<RowDefinition Height="60" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<Image Grid.Column="0" Grid.Row="0" Grid.RowSpan="3" HorizontalAlignment="Left" Name="image1" VerticalAlignment="Top" Source="........./el_bg.jpg" Stretch="None" />
<Grid Grid.Column="0" Grid.Row="1" VerticalAlignment="Top" Margin="2">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="200" />
<ColumnDefinition Width="100" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="50" />
</Grid.RowDefinitions>
<Image Grid.Column="0" Grid.Row="0" HorizontalAlignment="Left" Name="image2" Stretch="Fill" VerticalAlignment="Top" Source="........./shiny_rgb.png" />
<ListBox Grid.Column="2" Grid.Row="0" Name="MessageToUser" VerticalAlignment="Top">
<ListBoxItem>One</ListBoxItem>
<ListBoxItem>Two</ListBoxItem>
</ListBox>
</Grid>
</Grid>
</DockPanel>
In addition, your ListBox is in the third column of its containing Grid. If you want it to stretch across the entire window, you will need to ensure it spans all three columns:
<ListBox Grid.ColumnSpan="3" Grid.Row="0" Name="MessageToUser"
VerticalAlignment="Top">
You should read up on WPF layout - you're setting way more properties here than you need to be. Once you understand it, you'll find this thing much more intuitive. In addition, you can use a tool like Snoop to help figure out what is wrong with your layout.

Applying the following style helped me meet this requirement:
<Style x:Key="listBoxAutoFill" TargetType="ListBoxItem">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ListBoxItem}">
<Border x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}"
Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true">
<ContentPresenter HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsSelected" Value="true">
<Setter Property="Background" TargetName="Bd"
Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}"/>
<Setter Property="Foreground"
Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}"/>
</Trigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsSelected" Value="true"/>
<Condition Property="Selector.IsSelectionActive" Value="false"/>
</MultiTrigger.Conditions>
<Setter Property="Background" TargetName="Bd"
Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
<Setter Property="Foreground"
Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
</MultiTrigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground"
Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
My requirement is more about resizing the listbox height as the window grows/shrinks but the same can be applied for width.
<ListBox Grid.Row="1" Grid.Column="0" Width="158"
ItemContainerStyle="{StaticResource listBoxAutoFill}"
ItemsSource="{Binding ListBoxItems, Mode=TwoWay}" />