Strange behavior of GridSplitter - wpf

Question

can say that I am a beginner in WPF.
I have a strange behavior of GridSplitter; the grid is divided into 5 roww.
tabbar
horizontal grid
splitter
another tabbar
a textbox (txtLog)
like code below, but when I moving the separator the txtLog moves down instead of following the previous tabbar.
XAML:
<Window x:Class="MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:MSCSimulator"
mc:Ignorable="d"
FontSize="14"
Title="Simulator"
Height="500" Width="800"
WindowStartupLocation="CenterScreen"
WindowStyle="ThreeDBorderWindow">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="50" MinHeight="50" />
<RowDefinition Height="*" MinHeight="120" />
<RowDefinition Height="10" />
<RowDefinition Height="50" MinHeight="50" />
<RowDefinition Height="*" MinHeight="120" />
</Grid.RowDefinitions>
<!-- TOOLBAR -->
<ToolBarTray Margin="10,10,10,10" Width="Auto" Height="30">
<ToolBar Width="Auto" Height="30">
<Button Click="Send_Click">
<StackPanel Orientation="Horizontal">
<Image Source="/Simulator;component/Images/play.png" Width="12" Height="12" />
<Label Padding="5,0,0,0">Invia</Label>
</StackPanel>
</Button>
</ToolBar>
</ToolBarTray>
<Grid Grid.Row="1">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="220" MinWidth="150" MaxWidth="220" />
<ColumnDefinition Width="10" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<TreeView Width="Auto" Margin="10,0,0,0">
<TreeViewItem Header="Commands" IsExpanded="True">
<!-- APPLICATION -->
<TreeViewItem Header="Application">
<TreeViewItem Header="Simulate" MouseDoubleClick="Application_Simulate_MouseDoubleClick" />
<TreeViewItem Header="Update" MouseDoubleClick="Application_Update_MouseDoubleClick" />
</TreeViewItem>
</TreeViewItem>
<TreeView.Resources>
<Style TargetType="{x:Type TreeViewItem}">
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="FontWeight" Value="Bold"/>
</Trigger>
<Trigger Property="IsSelected" Value="False">
<Setter Property="FontWeight" Value="Normal"/>
</Trigger>
</Style.Triggers>
</Style>
</TreeView.Resources>
</TreeView>
<GridSplitter Width="10"
Background="White"
VerticalAlignment="Stretch"
ResizeBehavior="BasedOnAlignment" />
<!-- JSON -->
<TextBox Name="txtJSON"
Grid.Column="2"
Background="White"
TextWrapping="Wrap"
AcceptsReturn="True"
Margin="-10,0,10,0"
VerticalScrollBarVisibility="Visible"
Width="Auto" Height="Auto" />
</Grid>
<GridSplitter Grid.Row="2"
Height="10"
ResizeDirection="Rows"
HorizontalAlignment="Stretch"
ResizeBehavior="PreviousAndNext"
Background="White"/>
<!-- TOOLBAR -->
<ToolBarTray Grid.Row="3" Margin="10,0,10,0" Width="Auto" Height="30" VerticalAlignment="Top">
<ToolBar Width="Auto" Height="30">
<Button Click="Clear_Click">
<StackPanel Orientation="Horizontal">
<Image Source="/Simulator;component/Images/clear.png" Width="16" Height="16" />
<Label Padding="5,0,0,0">Cancella</Label>
</StackPanel>
</Button>
</ToolBar>
</ToolBarTray>
<!-- LOGGER-->
<TextBox Name="txtLog"
Grid.Row="4"
TextWrapping="Wrap"
Margin="10,-10,10,10"
AcceptsReturn="True"
VerticalScrollBarVisibility="Auto"
Width="Auto" Height="Auto"
IsReadOnly="True">
<TextBox.Background>
<SolidColorBrush Color="#282828"></SolidColorBrush>
</TextBox.Background>
<TextBox.Foreground>
<SolidColorBrush Color="White"></SolidColorBrush>
</TextBox.Foreground>
</TextBox>
</Grid>
thanks advance

Answer 1

In your outer Grid, try to put the Height from * to Auto in the second RowDefinition
...
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="50" MinHeight="50" />
<RowDefinition Height="Auto" MinHeight="120" />
<RowDefinition Height="10" />
<RowDefinition Height="50" MinHeight="50"/>
<RowDefinition Height="*" MinHeight="120" />
</Grid.RowDefinitions>
<!-- TOOLBAR -->
...