How to change insert direction to ItemsControl - wpf

Question

I have a control - ItemsControl that was binding to ObservableCollection of a simple model,
I want that it's itemscontrol will have a capability to insert dircetion from bottom to top, How to i can implement that?
Currently, Every insertion to itemscontrol starts from the top to bottom, but i want to change that..
<Window >
<Window.Resources>
<DataTemplate x:Key="ModelTemplate" DataType="Model:Model">
<Grid
Tag="{Binding Path=Id}"
Background="Transparent">
<Border
Name="border"
Background="#2a3345"
BorderThickness="0"
CornerRadius="10"
Margin="10">
<Border.Effect>
<DropShadowEffect
ShadowDepth="0"
Opacity="0.8"
BlurRadius="10"/>
</Border.Effect>
<Grid
Height="100"
Width="280"
Margin="6">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"></RowDefinition>
<RowDefinition Height="*"></RowDefinition>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"></ColumnDefinition>
<ColumnDefinition Width="*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<TextBlock
Grid.Column="1"
Text="{Binding Path=Title}"
TextOptions.TextRenderingMode="ClearType"
TextOptions.TextFormattingMode="Display"
Foreground="White"
FontFamily="Arial"
FontSize="14"
FontWeight="Bold"
VerticalAlignment="Center"
Margin="2,4,4,2"
TextWrapping="Wrap"
TextTrimming="CharacterEllipsis" />
<TextBlock
Grid.Row="1"
Grid.Column="1"
Text="{Binding Path=Message}"
TextOptions.TextRenderingMode="ClearType"
TextOptions.TextFormattingMode="Display"
Foreground="White"
FontFamily="Arial"
VerticalAlignment="Center"
Margin="2,2,4,4"
TextWrapping="Wrap"
TextTrimming="CharacterEllipsis"/>
</Grid>
</Border>
</Grid>
</DataTemplate>
</Window.Resources>
<Grid>
<ItemsControl
FocusVisualStyle="{x:Null}"
ItemsSource="{Binding SimpleCollection}"
ItemTemplate="{StaticResource ModelTemplate}" >
</ItemsControl>
</Grid>

Answer 1

The solution is override ItemsControl's ItemsPanel as follows:
<Window >
<Window.Resources>
<ScaleTransform ScaleY="-1" x:Key="Transform"/>
<DataTemplate x:Key="ModelTemplate" DataType="Model:Model">
<Grid
LayoutTransform="{StaticResource Transform}"
Tag="{Binding Path=Id}"
Background="Transparent">
<Border
Name="border"
Background="#2a3345"
BorderThickness="0"
CornerRadius="10"
Margin="10">
<Border.Effect>
<DropShadowEffect
ShadowDepth="0"
Opacity="0.8"
BlurRadius="10"/>
</Border.Effect>
<Grid
Height="100"
Width="280"
Margin="6">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"></RowDefinition>
<RowDefinition Height="*"></RowDefinition>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"></ColumnDefinition>
<ColumnDefinition Width="*"></ColumnDefinition>
</Grid.ColumnDefinitions>
<TextBlock
Grid.Column="1"
Text="{Binding Path=Title}"
TextOptions.TextRenderingMode="ClearType"
TextOptions.TextFormattingMode="Display"
Foreground="White"
FontFamily="Arial"
FontSize="14"
FontWeight="Bold"
VerticalAlignment="Center"
Margin="2,4,4,2"
TextWrapping="Wrap"
TextTrimming="CharacterEllipsis" />
<TextBlock
Grid.Row="1"
Grid.Column="1"
Text="{Binding Path=Message}"
TextOptions.TextRenderingMode="ClearType"
TextOptions.TextFormattingMode="Display"
Foreground="White"
FontFamily="Arial"
VerticalAlignment="Center"
Margin="2,2,4,4"
TextWrapping="Wrap"
TextTrimming="CharacterEllipsis"/>
</Grid>
</Border>
</Grid>
</DataTemplate>
<ItemsPanelTemplate x:Key="ItemsPanelTemplateVerticalAlignment">
<StackPanel VerticalAlignment="Bottom" LayoutTransform="{StaticResource Transform}"/>
</ItemsPanelTemplate>
</Window.Resources>
<Grid>
<ItemsControl
FocusVisualStyle="{x:Null}"
ItemsSource="{Binding SimpleCollection}"
ItemTemplate="{StaticResource ModelTemplate}"
ItemsPanel="{StaticResource ItemsPanelTemplateVerticalAlignment}"/>
</Grid>
</Window>

Answer 2

The order of items in ItemsControl is the same as in ObservableCollection. Thus, if you do Collection.Insert(0, item), new item in ItemsControl will appear on the top.