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GridSplitter getting stuck after dragging some pixels

GridSplitter getting stuck after dragging some pixels,and have to reselect the splitter and drag again.
I am using RadTreeView in one column, and ListBox in second column, in which user can select Item from ListBox and Drag it into RadTreeView.
Please find below screenshot for the UI.
I tried to find solution on SO, but not getting any useful answer.
Please find below code for the same, Let me know if you require more information for the same.
<UserControl x:Class="StructureDesigner.StructureDesigner"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
xmlns:dragDrop="clr-namespace:Telerik.Windows.Controls.DragDrop;assembly=Telerik.Windows.Controls"
xmlns:vm="clr-namespace:StructureDesigner.ViewModel"
MinHeight="400" MinWidth="400" AllowDrop="True" telerik:DragDropManager.AllowCapturedDrag="True" Name="StructureDesignerScreen">
<UserControl.Resources>
<Style TargetType="telerik:RadTreeViewItem">
<Setter Property="AllowDrop" Value="true" />
<Setter Property="telerik:DragDropManager.AllowCapturedDrag" Value="True" />
<Setter Property="telerik:DragDropManager.AllowDrag" Value="True" />
</Style>
<Style TargetType="ListBoxItem">
<Setter Property="telerik:DragDropManager.AllowCapturedDrag" Value="True" />
</Style>
</UserControl.Resources>
<Grid x:Name="MainGrid" ScrollViewer.CanContentScroll="false" ScrollViewer.HorizontalScrollBarVisibility="Hidden" ScrollViewer.VerticalScrollBarVisibility="Hidden">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="300"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<GridSplitter x:Name="gridSplitter" Grid.Row="0" Grid.Column="0" HorizontalAlignment="Right" Width="10" Background="DarkGray" Height="Auto" />
<telerik:RadTreeView x:Name="radStructureTreeView" IsDragTooltipEnabled="True" IsDragDropEnabled="True"
IsDragPreviewEnabled="True" IsDropPreviewLineEnabled="True"
Grid.Row="0" Grid.Column="0" SelectionMode="Extended"
HorizontalAlignment="Stretch" Margin="2,2,11,2" IsLoadOnDemandEnabled="True"
LoadOnDemand="radStructureTreeView_LoadOnDemand"
ExpanderStyle="{StaticResource ExpanderStyle}"
ItemContainerStyle="{StaticResource ItemContainerStyle}"
IsExpandOnSingleClickEnabled="False" ItemsSource="{Binding StructureDesignerList}"
ItemTemplate="{StaticResource NavigationTemplate}"
telerik:TreeViewSettings.DragDropExecutionMode="New"
>
</telerik:RadTreeView>
<Grid Grid.Row="0" Grid.Column="1" Name="gridEntities" HorizontalAlignment="Stretch" Margin="1,2,2,2">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<ListBox x:Name="listBox1" Grid.Row="0" Grid.Column="0" Margin="8" HorizontalAlignment="Stretch"
SelectionMode="Extended" Width="Auto" ItemsSource="{Binding EntityList}"
AllowDrop="True">
<ListBox.ContextMenu>
<ContextMenu>
<MenuItem Header="Hide posted entities" Tag="Hide posted entities" IsCheckable="True" IsChecked="{Binding Path=IsHidePostedEntitiesChecked}"></MenuItem>
</ContextMenu>
</ListBox.ContextMenu>
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Vertical">
<Label Name="lblSpacer1" Height="5"></Label>
<StackPanel Orientation="Horizontal">
<Image Grid.Column="1" Width="25" Height="16" Source="{Binding Path=Icon}" VerticalAlignment="Top"></Image>
<Label Content="" Width="1" Height="16" ></Label>
<TextBlock Text="{Binding Description}" FontWeight="Bold" VerticalAlignment="Center" />
</StackPanel>
<Label Name="lblSpacer2" Height="5"></Label>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</Grid>
</UserControl>

Stretching a user control in a grid view

I have a usercontrol in a GridView in a uwp app.I want the usercontrol to be stretched in the Gridview's ItemsPanel. I tried to set the HorizontolAlignment of the usercontrol to Stretchbut no success.Someone knows the solution?
here's the xaml of the usercontrol
<UserControl
x:Class="LessonsBuild.Controls.TextItemControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:LessonsBuild.Controls"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="300"
d:DesignWidth="614"
HorizontalAlignment="Stretch"
Margin="5"
Height="Auto">
<Grid Width="{Binding RelativeSource={RelativeSource Mode=TemplatedParent },Path=Width}"
Height="Auto" >
<Rectangle x:Name="DropShadow"
Margin="5,5,0,0"
Fill="{StaticResource DropShadowBrush }"/>
<Grid x:Name="Root"
Width ="{Binding RelativeSource={RelativeSource Mode=TemplatedParent },Path=Width}"
Height="Auto"
Margin="0,0,3,3"
Background="White" >
<Grid.RowDefinitions >
<RowDefinition Height="Auto" />
<RowDefinition />
</Grid.RowDefinitions>
<!--#region Header-->
<Grid Width="{Binding RelativeSource={RelativeSource Mode=TemplatedParent },Path=Width}"
HorizontalAlignment="Stretch" >
<Grid.ColumnDefinitions >
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<TextBlock x:Name="txtTitel"
Text="{x:Bind CurrentModel.Title}"
FontSize="30"
VerticalAlignment="Top" />
<StackPanel x:Name="controls"
Grid.Column="1"
Orientation="Horizontal" >
<AppBarButton x:Name="btnBold"
Icon="Bold"
Click="btnBold_Click" />
<AppBarButton x:Name="btnItalic"
Icon="Italic"
Click="btnItalic_Click" />
<AppBarButton x:Name="btnUnderline"
Icon="Underline"
Click="btnUnderline_Click" />
<AppBarButton x:Name="btnBullet"
Icon="Bullets"
Click="btnBullet_Click" />
</StackPanel>
<AppBarButton x:Name="btnDelete"
Grid.Column="2"
HorizontalAlignment="Right"
Icon="Delete"
Click="btnDelete_Click"
/>
</Grid>
<!--#endregion-->
<!--#region Content-->
<RichEditBox x:Name="txtBox"
Grid.Row="1" BorderThickness="0,1"
TextChanged="txtBox_TextChanged"
>
</RichEditBox>
<!--#endregion-->
</Grid>
</Grid>
Heres the GridViews xaml
<GridView Grid.Row="1"
Margin="30"
ItemsSource="{Binding TextControlList}" SelectionMode="None"
HorizontalContentAlignment="Stretch" />

To adjust it, modify the item of HorizontalContentAlignment as Stretch, within the 'ItemContainerStyle' (NOT within the gridview itself).
In list/gridview control, you can modify the way of item placement via this ItemContainerStyle.
<GridView x:Name="yourGridView" .... >
<GridView.ItemContainerStyle>
<Style TargetType="GridViewItem">
<Setter Property="HorizontalContentAlignment" Value="Stretch"/>
</Style>
</GridView.ItemContainerStyle>
</GridView>

Try to use a ListView instead of a GridView

Black Background occurs when using microsoft.windows.shell

I am using the microsoft.windows.shell to customize my wpf window chrome. Everything is fine until I added a datagrid. The problem is that the appearance of the window become black sometimes. This situation does not happen constantly! Sometimes it looks fine but sometimes it has a black background.
Here is my xaml code:
<Window x:Class="CodeGeneratorWpf.Config"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Config" Height="300" Width="300" Style="{StaticResource MainWindowStyle}"
WindowStartupLocation="CenterOwner" Loaded="Window_Loaded">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="40"/>
</Grid.RowDefinitions>
<DataGrid Name="dataGrid" Grid.Row="0" ItemsSource="{Binding data}"
AlternatingRowBackground="{StaticResource {x:Static SystemColors.ControlBrushKey}}"
ClipToBounds="True" VerticalGridLinesBrush="{DynamicResource {x:Static SystemColors.ControlLightBrushKey}}"
HorizontalGridLinesBrush="{DynamicResource {x:Static SystemColors.ControlLightBrushKey}}"
LoadingRow="dataGrid_LoadingRow">
<DataGrid.RowHeaderTemplate>
<DataTemplate>
<TextBlock Text="{Binding RelativeSource={RelativeSource AncestorType=DataGridRow},
Path=Header}"/>
</DataTemplate>
</DataGrid.RowHeaderTemplate>
</DataGrid>
<Grid Grid.Row="1">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Button Name="btnSave" Grid.Column="0" Content="Save" Style="{StaticResource EmphasizeButton}" HorizontalAlignment="Stretch" Margin="25,5,25,5" Click="btnSave_Click"/>
<Button Name="btnCancel" Grid.Column="1" Content="Cancel" Style="{StaticResource NormalButton}" Margin="25,5,25,5" Click="btnCancel_Click"/>
</Grid>
</Grid>
</Window>
The MainWindowStyle:
<!--Captions Buttons to control the window borderless-->
<DockPanel Grid.Row="0">
<DockPanel.Background>
<SolidColorBrush Color="#FF5D91DC"></SolidColorBrush>
</DockPanel.Background>
<Image Name="imgTitle" Source="{TemplateBinding Icon}" DockPanel.Dock="Left" Margin="5"></Image>
<Label Content="{TemplateBinding Title}" Foreground="White"></Label>
<ctrl:CaptionButtons Margin="0,0,0,0" Grid.Row="0" HorizontalAlignment="Right" Type="Full"
Foreground="{DynamicResource CaptionButtonColor}" FontSize="14" MarginButton="0,0,5,0"
VerticalAlignment="Center" shell:WindowChrome.IsHitTestVisibleInChrome="True">
</ctrl:CaptionButtons>
</DockPanel>
<ContentPresenter Margin="0" Grid.Row="1" Content="{TemplateBinding Content}"/>
</Grid>
</Border>
</ControlTemplate>
<Style x:Key="MainWindowStyle" TargetType="{x:Type Window}">
<Setter Property="shell:WindowChrome.WindowChrome">
<Setter.Value>
<shell:WindowChrome
ResizeBorderThickness="6"
CaptionHeight="25"
CornerRadius="0"
GlassFrameThickness="0,0,0,1" />
</Setter.Value>
</Setter>
<Setter Property="Template" Value="{StaticResource MainWindowControlTemplate}"/>
</Style>
Can I get some help?

How to make the scrollviewer work in this scenario?

Having some problems with my MVVM Application.
So the scenario is the following:
In my MainWindow.xaml, I have a ContentControl placed in a Grid Column, its content is bind to the CurrentViewModel which will be rendered to the appropriate View (in this case, Overview.xaml).
<ContentControl Grid.Row="1" Grid.Column="1" Content="{Binding CurrentViewModel}">
Within this particular view (Overview.xaml) there are multiple UserControls placed within a StackPanel.
<ScrollViewer CanContentScroll="True" VerticalScrollBarVisibility="Visible" HorizontalScrollBarVisibility="Visible">
<StackPanel CanVerticallyScroll="True" CanHorizontallyScroll="True">
<views:DiagramView DataContext="{Binding Path=DiagramViewModel, Source={StaticResource Locator}}" />
<views:IncomeCollectionView DataContext="{Binding Path=IncomesViewModel, Source={StaticResource Locator}}" />
<views:ExpenseCollectionView DataContext="{Binding Path=ExpensesViewModel, Source={StaticResource Locator}}" />
<views:CheckCollectionView DataContext="{Binding Path=ChecksViewModel, Source={StaticResource Locator}}" />
<views:BalanceCollectionView DataContext="{Binding Path=BalancesViewModel, Source={StaticResource Locator}}" />
<views:VacationCollectionView DataContext="{Binding Path=VacationsViewModel, Source={StaticResource Locator}}" />
<views:KHCollectionView DataContext="{Binding Path=KhViewModel, Source={StaticResource Locator}}" />
<views:OctaviaCollectionView DataContext="{Binding Path=OctaviaViewModel, Source={StaticResource Locator}}" />
</StackPanel>
</ScrollViewer>
Each UserControl within this StackPanel has a very similar look (obviously there are more stuff in the XAML). There is no constant value regarding Width or Height within my application.
<ListView ItemsSource="{Binding Source={StaticResource groupedCollection}}" SelectedItem="{Binding CurrentItem}">
<ListView.GroupStyle>
<GroupStyle>
<GroupStyle.HeaderTemplate>
<DataTemplate>
<TextBlock Text="{Binding Items[0].CurrentCategory}" />
</DataTemplate>
</GroupStyle.HeaderTemplate>
</GroupStyle>
</ListView.GroupStyle>
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<UniformGrid Columns="12" Rows="1" />
</ItemsPanelTemplate>
</ListView.ItemsPanel>
<ListView.ItemContainerStyle>
<Style>
<Setter Property="Grid.Column" Value="{Binding GeneratedColumn}"/>
</Style>
</ListView.ItemContainerStyle>
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel>
<TextBlock Text="{Binding EncryptedAmount}" />
<StackPanel Orientation="Horizontal">
<TextBlock Text="Got paid on " />
<TextBlock Text="{Binding Date}" />
</StackPanel>
<Button Content="details"
Command="{Binding Path=DataContext.ShowDialogCommand,
RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}"
CommandParameter="QuickEdit"/>
<Button Content="remove" Command="{Binding RemoveCommand}" CommandParameter="Income removed." />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
The problem is that I can't seem to make the vertical scrollviewer work. It is displayed because I make it visible, but it's disabled. Obviously the StackPanel is gonna grow indefintely, but isn't there a way for it to calculate how much space is needed? Because most of the content is just cut off right now.
So I tried to put scrollviewer in every possible place, but they're all disabled.
<Style TargetType="{x:Type ContentControl}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ContentControl">
<ScrollViewer>
<ContentPresenter Cursor="{TemplateBinding Cursor}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
Margin="{TemplateBinding Padding}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
Content="{TemplateBinding Content}" ContentTemplate="{TemplateBinding ContentTemplate}"/>
</ScrollViewer>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
So then I tried dropping the StackPanel implementation and tried it with a Grid.
Nope, it doesn't work either.
Obviously I'm missing some basis solution here, but just can't figure it out.
Any ideas would be appreciated, seems like a very common scenario to be honest.
Cheers
<ScrollViewer CanContentScroll="True"
VerticalScrollBarVisibility="Visible"
HorizontalScrollBarVisibility="Visible">
<Grid>
<Grid.RowDefinitions>
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
<RowDefinition />
</Grid.RowDefinitions>
<views:DiagramView DataContext="{Binding Path=DiagramViewModel, Source={StaticResource Locator}}" />
<views:IncomeCollectionView Grid.Row="1" DataContext="{Binding Path=IncomesViewModel, Source={StaticResource Locator}}" />
<views:ExpenseCollectionView Grid.Row="2" DataContext="{Binding Path=ExpensesViewModel, Source={StaticResource Locator}}" />
<views:CheckCollectionView Grid.Row="3" DataContext="{Binding Path=ChecksViewModel, Source={StaticResource Locator}}" />
...etc...
</Grid>
</ScrollViewer>
Edit: The DiagramView UserControl contains the following:
<UserControl x:Class="Expense.Manager.WPF.Views.DiagramView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:pie="clr-namespace:Expense.Manager.WPF.CustomPie"
xmlns:local="clr-namespace:Expense.Manager.WPF.Shared"
mc:Ignorable="d">
<UserControl.Resources>
<local:BoolToBrushConverter x:Key="BoolToBrushConverter" />
</UserControl.Resources>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<StackPanel>
<StackPanel Orientation="Horizontal">
<TextBlock Text="Income this month: " />
<TextBlock>
<TextBlock.Text>
<PriorityBinding FallbackValue="Retrieving data...">
<Binding Path="EncryptedCurrentMonthIncome" Mode="TwoWay" IsAsync="True" />
</PriorityBinding>
</TextBlock.Text>
</TextBlock>
</StackPanel>
<pie:PieChart Data="{Binding PieChartIncomeData, Mode=TwoWay}" Width="250" PieWidth="130" PieHeight="130" Height="140" />
</StackPanel>
<StackPanel Grid.Row="0" Grid.Column="1">
<StackPanel Orientation="Horizontal">
<TextBlock Text="Expenses this month: " />
<TextBlock>
<TextBlock.Text>
<PriorityBinding FallbackValue="Retrieving data...">
<Binding Path="CurrentMonthExpense" Mode="TwoWay" IsAsync="True" />
</PriorityBinding>
</TextBlock.Text>
</TextBlock>
</StackPanel>
<pie:PieChart Data="{Binding PieChartExpenseData, Mode=TwoWay}" Width="250" PieWidth="130" PieHeight="130" Height="140" />
</StackPanel>
<StackPanel Grid.Column="2">
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding VacationsLeft}" />
<TextBlock Text=" days left" />
</StackPanel>
<ItemsControl ItemsSource="{Binding VacationsPerYearCollection}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Rectangle Margin="5, 0, 0, 0" Height="25" Width="4" Fill="{Binding Converter={StaticResource BoolToBrushConverter}}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
<StackPanel Orientation="Horizontal">
<TextBlock Text="Bank savings:" />
<TextBlock Text="{Binding BankSavings}" />
</StackPanel>
</StackPanel>
</Grid>
IncomeCollectionView:
<UserControl x:Class="Expense.Manager.WPF.Views.IncomeCollectionView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:views="clr-namespace:Expense.Manager.WPF.Views"
mc:Ignorable="d">
<UserControl.Resources>
<CollectionViewSource x:Key="groupedCollection" IsLiveGroupingRequested="True" Source="{Binding Collection}">
<CollectionViewSource.GroupDescriptions>
<PropertyGroupDescription PropertyName="CurrentCategory" />
</CollectionViewSource.GroupDescriptions>
</CollectionViewSource>
</UserControl.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<TextBlock Text="{Binding DisplayName}" Foreground="White" FontWeight="SemiBold" Padding="5" Background="SteelBlue" />
<ListView Grid.Row="1" ItemsSource="{Binding Source={StaticResource groupedCollection}}" SelectedItem="{Binding CurrentItem}">
<ListView.GroupStyle>
<GroupStyle>
<GroupStyle.HeaderTemplate>
<DataTemplate>
<TextBlock Text="{Binding Items[0].CurrentCategory}" />
</DataTemplate>
</GroupStyle.HeaderTemplate>
</GroupStyle>
</ListView.GroupStyle>
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<UniformGrid HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Columns="12" Rows="1" />
</ItemsPanelTemplate>
</ListView.ItemsPanel>
<ListView.ItemContainerStyle>
<Style>
<Setter Property="Grid.Column" Value="{Binding GeneratedColumn}"/>
</Style>
</ListView.ItemContainerStyle>
<ListView.ItemTemplate>
<DataTemplate>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<TextBlock Text="{Binding EncryptedAmount}" />
<TextBlock Grid.Row="1" Text="{Binding Date}" />
<Button Grid.Row="2" Content="details"
Command="{Binding Path=DataContext.ShowDialogCommand,
RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}"
CommandParameter="QuickEdit"/>
<Button Grid.Row="3" Content="remove" Command="{Binding RemoveCommand}" CommandParameter="Income removed." />
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</Grid>
and where it is used:
why is the listview not resizing itself after resizing the window itself?
<ScrollViewer CanContentScroll="True" HorizontalScrollBarVisibility="Visible" VerticalScrollBarVisibility="Visible">
<Grid HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<views:IncomeCollectionView Grid.Row="1" DataContext="{Binding Path=IncomesViewModel, Source={StaticResource Locator}}" />
</Grid>
</ScrollViewer>

I tried dropping the StackPanel implementation and tried it with a Grid. Nope, it doesn't work either.
That's almost correct, apart from the last sentence. Using a Grid is half of the answer, because the StackPanel has no functionality to resize its items... you just need to inform the ScrollViewer when to scroll. Take this example:
<ScrollViewer>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="50" />
<RowDefinition Height="50" />
<RowDefinition Height="50" />
<RowDefinition Height="50" />
<RowDefinition Height="50" />
<RowDefinition Height="50" />
<RowDefinition Height="50" />
</Grid.RowDefinitions>
<Rectangle Fill="Cyan" />
<Rectangle Grid.Row="1" Fill="Green" />
<Rectangle Grid.Row="2" Fill="Red" />
<Rectangle Grid.Row="3" Fill="Blue" />
<Rectangle Grid.Row="4" Fill="Orange" />
<Rectangle Grid.Row="5" Fill="Purple" />
<Rectangle Grid.Row="6" Fill="Yellow" />
</Grid>
</ScrollViewer>
This XAML will make the ScrollViewer ScrollBar appear (once the Window.Height is small enough), but if you remove the RowDefinition.Height values (thereby giving each row a proportion of the whole Grid.Height), you'll see your previous situation where no ScrollBar appears.
Now, none of us want to hard code constant values into our UIs, but you can do this using the Auto setting on the RowDefinition.Height properties instead. Unlike these Rectangles, your controls will all have some Height, so your solution is to set each of your Grid.RowDefinitions like this:
<RowDefinition Height="Auto" />
This will provide your controls with as much space as they need within the Grid and therefore (hopefully) they will have more Height together than the ScrollViewer and therefore the ScrollViewer will display its vertical ScrollBar.

Why is two-way data-binding not working in WPF?

I am working on a small university project where I need to read a Lua file with some tables and functions and make a shape out of it. That's done.
The problem is when I try to make it interactive. Here's my XAML:
<Window x:Class="Gemi.WPF.VentanaPrincipal"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:Gemi.WPF"
Title="GEMI - Geometría Interactiva!" Height="350" Width="525">
<Window.Resources>
<local:DoblesAPunto x:Key="DoblesAPunto"/>
</Window.Resources>
<DockPanel LastChildFill="True" Background="White">
<Grid DockPanel.Dock="Top">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Label Content="Figura Seleccionada: "/>
<ComboBox Name="cbFiguras" HorizontalAlignment="Stretch" Grid.Column="1"
ItemsSource="{Binding Path=Figuras}" DisplayMemberPath="Nombre" SelectionChanged="cbFiguras_FiguraSeleccionada" />
</Grid>
<ScrollViewer DockPanel.Dock="Bottom" Name="scrollPropiedades"
Height="Auto" VerticalScrollBarVisibility="Auto">
<DockPanel Name="dpPropiedades">
<StackPanel Orientation="Vertical" Name="spNombres" DockPanel.Dock="Left"/>
<StackPanel Orientation="Vertical" Name="spValores" DockPanel.Dock="Right" Margin="10, 0, 0, 0"/>
</DockPanel>
</ScrollViewer>
<DockPanel LastChildFill="True">
<Slider Name="controlZoom" DockPanel.Dock="Bottom" Value="1"
Maximum="50" Minimum="0.1" Orientation="Horizontal" ToolTip="Controla el zoom de la figura"/>
<ItemsControl x:Name="cnvFigura" ItemsSource="{Binding Puntos}">
<ItemsControl.LayoutTransform>
<ScaleTransform
CenterX="0" CenterY="0"
ScaleX="{Binding ElementName=controlZoom,Path=Value}"
ScaleY="{Binding ElementName=controlZoom,Path=Value}"/>
</ItemsControl.LayoutTransform>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Path Fill="Black" local:DragCanvas.CanBeDragged="True"
local:DragCanvas.Top="{Binding Y, Mode=TwoWay}"
local:DragCanvas.Left="{Binding X, Mode=TwoWay}">
<Path.Data>
<EllipseGeometry RadiusX="5" RadiusY="5">
<EllipseGeometry.Center>
<MultiBinding Converter="{StaticResource DoblesAPunto}">
<Binding Path="X" />
<Binding Path="Y" />
</MultiBinding>
</EllipseGeometry.Center>
</EllipseGeometry>
</Path.Data>
<Path.ToolTip>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<TextBlock Text="X = " Grid.Column="0" Grid.Row="0"/>
<TextBlock Text="{Binding X}" Grid.Column="1" Grid.Row="0"/>
<TextBlock Text="Y = " Grid.Column="0" Grid.Row="1"/>
<TextBlock Text="{Binding Y}" Grid.Column="1" Grid.Row="1"/>
</Grid>
</Path.ToolTip>
</Path>
</DataTemplate>
</ItemsControl.ItemTemplate>
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<local:DragCanvas IsItemsHost="True"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
</DockPanel>
</DockPanel>
</Window>
The issue in question is that the binding does not update. The "Punto" object's setters are never called even if I drag the ellipses making up the DataTemplate. Any ideas?
Also, why do I seem to need to bind the center of the ellipses? If I only bind DragCanvas' Top/Bottom/Left/Right all the points are drawn at 0,0, and this induces a problem as i can't drag the points further left nor top where they initially were.

This might be caused because Drag-n-drop does not modify the Canvas.Left and Canvas.Top but instead uses a Transformation (Translation).
Binding to this Translation might be tricky because I expect that the drag-n-drop system adds this transformation to the transformation group. So it will not update a translation you added to the Transformations.