Cannot get TextBoxes(2) to fill grid space

Question

So I'm convinced that this is probably an easy answer and I'm just not seeing it, but after 20 google searches and 3 days of trying to figure it out on my own, I surrender. The xaml I'm using is below. What I need is for the two textboxes to fill all remaining space and to be equally sized. I've tried StackPanel, DockPanel, Grid (as it is below), and even nesting each of these and nesting a UniformGrid. Nothing seems to work, I just get 2 textboxes with whatever height I specify for MinHeight. Changing the Grid.Row setting from Auto to * just results in the TextBoxes centering themselves and moving as the window shrinks and grows.

        <TabItem Header="Notes" Name="notesTab">
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*"/>
                    <ColumnDefinition Width="Auto"/>
                </Grid.ColumnDefinitions>
                <Grid.RowDefinitions>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="23"/>
                    <RowDefinition Height="Auto"/>
                </Grid.RowDefinitions>
                <Label Content="Select Contact:" Height="28" Grid.Row="0" Grid.Column="0" HorizontalAlignment="Right" FontStyle="Italic" FontWeight="Bold"></Label>
                <ComboBox Grid.Column="1" Grid.Row="0" Height="23" HorizontalAlignment="Right" Width="150" ItemsSource="{Binding Source={StaticResource contactList}}" DataContext="{Binding Source={StaticResource contactList}}" Name="contactSelectionBox"></ComboBox>
                <WrapPanel Grid.Row="1" Height="Auto" Grid.ColumnSpan="2" Margin="5">
                    <WrapPanel.Width>
                        <Binding ElementName="callNotes" Path="ActualWidth" />
                    </WrapPanel.Width>
                    <Label Content="TAD" Width="Auto" Name="tadShortcut" MouseLeftButtonDown="tadShortcut_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="VI" Width="Auto" Name="verifyInfoShortcut" MouseLeftButtonDown="verifyInfoShortcut_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="Not there" Width="Auto" Name="uipShortcut" MouseLeftButtonDown="uipShortcut_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="WUSP" Width="Auto" Name="wuspShortcut" MouseLeftButtonDown="wuspShortcut_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="FNYD" Width="Auto" Name="fnydShortcut" MouseLeftButtonDown="fnydShortcut_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="Not Employed" Width="Auto" Name="notEmployedShortcut" MouseLeftButtonDown="notEmployedShortcut_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="Message" Width="Auto" Name="messageShortcut" MouseLeftButtonDown="messageShortcut_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="Late Fees" Width="Auto" Name="lateFeesShortcut" MouseLeftButtonDown="lateFeesShortcut_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="Payoff" Width="Auto" Name="payoffReqShortcut" MouseLeftButtonDown="payoffReqShortcut_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="No Commit" Width="Auto" Name="noCommit" MouseLeftButtonDown="noCommit_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="12/12" Width="Auto" Name="twelve12" MouseLeftButtonDown="twelve12_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="No ID" Width="Auto" Name="vmNoID" MouseLeftButtonDown="vmNoID_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="Wrong #" Width="Auto" Name="wrongNumber" MouseLeftButtonDown="wrongNumber_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="Day Off" Width="Auto" Name="dayOff" MouseLeftButtonDown="dayOff_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="FPD" Width="Auto" Name="firstPaymentDefault" MouseLeftButtonDown="firstPaymentDefault_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="Repo Pmnt" Width="Auto" Name="repoPayment" MouseLeftButtonDown="repoPayment_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="CS Xfer" Width="Auto" Name="custServ" MouseLeftButtonDown="custServ_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                    <Label Content="Spanish" Width="Auto" Name="spanish" MouseLeftButtonDown="spanish_MouseLeftButtonDown" MouseEnter="notesLabel_MouseEnter" MouseLeave="notesLabel_MouseLeave" />
                </WrapPanel>
                <MyNamespace:WatermarkTextBox Grid.Row="2" Grid.ColumnSpan="2" Style="{StaticResource TextBox Style}" MinHeight="98" Margin="15,5,15,5" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" AcceptsReturn="True" TextWrapping="Wrap" VerticalScrollBarVisibility="Auto" Name="callTwoNotes"  TextChanged="callTwoNotes_TextChanged" FontWeight="Bold" IsEnabled="False" ClipToBounds="False"></MyNamespace:WatermarkTextBox>
                <Button Grid.Row="3" Grid.ColumnSpan="2" Height="23" Name="flipFlopButton" VerticalAlignment="Center" Width="75" Click="flipFlopButton_Click">
                        <Image Source="Images/FlipFlop.gif" />
                </Button>
                <MyNamespace:WatermarkTextBox Grid.Row="4" Grid.ColumnSpan="2" Style="{StaticResource TextBox Style}" MinHeight="98" Margin="15,5,15,5" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" AcceptsReturn="True" TextWrapping="Wrap" VerticalScrollBarVisibility="Auto" Name="callNotes"  TextChanged="callNotes_TextChanged" FontWeight="Bold"></MyNamespace:WatermarkTextBox>
            </Grid>
    </TabItem>

The xaml for the style on the TextBoxes is below, just for completeness.

<Style x:Key="TextBox Style" TargetType="{x:Type MyNamespace:WatermarkTextBox}">
        <Setter Property="CharacterCasing" Value="Upper" />
        <Setter Property="HorizontalAlignment" Value="Left" />
        <Setter Property="VerticalAlignment" Value="Top" />
        <Setter Property="Height" Value="23" />
        <Setter Property="Width" Value="Auto" />
        <Setter Property="SelectAllOnGotFocus" Value="True" />
    </Style>

Answer 1

There are two issues with the code posted

The Grid's RowDefintion for the TextBoxes is listed as Auto instead of * . This means the Row will be sized based on the size of the cell contents, not based on the Grid's size. Change this to * so it's size will be based on available space.

<Grid.RowDefinitions>
    <RowDefinition Height="Auto"/>
    <RowDefinition Height="Auto"/>
    <RowDefinition Height="*"/>
    <RowDefinition Height="23"/>
    <RowDefinition Height="*"/>
</Grid.RowDefinitions>

The other problem is your TextBox style is defining a Height for your item. This means it will keep the TextBox at the specified Height and not re-size it to fit the available space. You can either remove this style setter, or set the Height on your TextBoxes in the Grid to Auto.

Remove this setter

<Style x:Key="TextBox Style" TargetType="{x:Type MyNamespace:WatermarkTextBox}">
    <Setter Property="Height" Value="23" />
    ...
</Style>

Or set the Height property on your TextBox tag to Auto. Setting the property in the object's tag will overwrite a styled property

<MyNamespace:WatermarkTextBox Height="Auto" Grid.Row="2" ... />
<MyNamespace:WatermarkTextBox Height="Auto" Grid.Row="4" ... />

Answer 2

This was answered a few minutes ago by someone else but now the answer it gone. Try deleting these lines:

    <Setter Property="HorizontalAlignment" Value="Left" /> 
    <Setter Property="VerticalAlignment" Value="Top" />

As might be overwriting the Stretch

Answer 3

Edit: Ok i tried your code and what you need to change is your Grid RowDefinitions, try

<Grid.RowDefinitions>
    <RowDefinition Height="Auto"/>
    <RowDefinition Height="Auto"/>
    <RowDefinition Height="2*"/>
    <RowDefinition Height="23"/>
    <RowDefinition Height="2*"/>
</Grid.RowDefinitions>

and you might want to remove your minheight aswell. In fact, you should try to remove all you explicit heights and widths, let WPF take care of that, thats what the layout system is for.