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Make multi line design of tag control

I have applied the evernote tag control which is working but the design is not in multi line as I add tag it is added next to the previous tag and adding in the single line, but it has to move down when there is no more space on the page. Here is the screenshot of what I want:
I have followed this link : http://stackoverflow.com/questions/15167809/how-can-i-create-a-tagging-control-similar-to-evernote-in-wpf but still unable to get the tags in multi line. Please let me know where I am going wrong. Following is my xaml:
<!-- EvernoteTagControl default style -->
<Style TargetType="{x:Type local:EvernoteTagControl}">
<Style.Resources>
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="White"/>
<SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}" Color="White" />
<LinearGradientBrush x:Key="IconBrush" EndPoint="0,1">
<GradientStop Color="#5890f0" Offset="0" />
<GradientStop Color="#0351d7" Offset="1" />
</LinearGradientBrush>
</Style.Resources>
<Setter Property="FocusVisualStyle" Value="{x:Null}" />
<Setter Property="VerticalAlignment" Value="Top" />
<Setter Property="Margin" Value="15 25 15 15" />
<Setter Property="MinHeight" Value="25" />
<Setter Property="VerticalContentAlignment" Value="Center" />
<Setter Property="SnapsToDevicePixels" Value="True" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type local:EvernoteTagControl}">
<Grid>
<Grid.ColumnDefinitions>
<!--<ColumnDefinition Width="Auto" />-->
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<!--<Path Grid.Column="0" Margin="2" Fill="{StaticResource IconBrush}" Height="19" Stretch="Uniform" Data="M 50.535714,0.44196425 0.00446427,34.754464 l 0,106.906246 100.71874573,0 0,-107.124996 L 50.535714,0.44196425 z m 0.1875,21.21874975 c 6.311826,0 11.40625,5.094424 11.40625,11.40625 0,6.311826 -5.094424,11.4375 -11.40625,11.4375 -6.311826,0 -11.4375,-5.125674 -11.4375,-11.4375 0,-6.311826 5.125674,-11.40625 11.4375,-11.40625 z" />-->
<ItemsPresenter Grid.Column="0" Margin="2" />
<Button Margin="5,0,0,0" Grid.Column="1" Content="Click to add..." x:Name="PART_CreateTagButton">
<Button.Template>
<ControlTemplate TargetType="Button">
<ContentPresenter TextElement.Foreground="#FF555555" VerticalAlignment="Center" />
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Cursor" Value="Hand" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Button.Template>
</Button>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsEditing" Value="True">
<Setter TargetName="PART_CreateTagButton" Property="Visibility" Value="Collapsed" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Setter Property="ItemContainerStyle">
<Setter.Value>
<Style TargetType="{x:Type ListBoxItem}">
<Setter Property="FocusVisualStyle" Value="{x:Null}" />
</Style>
</Setter.Value>
</Setter>
<Setter Property="ItemsPanel" >
<Setter.Value>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
</Style>
<!-- EvernoteTagItem default style -->
<Style TargetType="{x:Type local:EvernoteTagItem}">
<Setter Property="FocusVisualStyle" Value="{x:Null}" />
<Setter Property="MinWidth" Value="50" />
<Setter Property="Margin" Value="0,0,2,0" />
<Setter Property="Padding" Value="5,2,0,2" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type local:EvernoteTagItem}">
<Button x:Name="PART_TagButton" Content="{TemplateBinding Text}" Foreground="#ffffff" Margin="{TemplateBinding Margin}" Padding="{TemplateBinding Padding}">
<Button.Template>
<ControlTemplate TargetType="Button">
<Border Margin="{TemplateBinding Margin}" Padding="{TemplateBinding Padding}" BorderBrush="#00698C" BorderThickness="1" CornerRadius="2" Background="#00698C" >
<Grid >
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<ContentPresenter VerticalAlignment="Center" HorizontalAlignment="Left" Margin="0,0,0,2" />
<Button x:Name="PART_DeleteTagButton" Grid.Column="1" Margin="3,0" VerticalAlignment="Center" HorizontalAlignment="Right" >
<Button.Template>
<ControlTemplate>
<Grid Height="10" Width="10" Background="#00698C" >
<Path Stretch="Uniform" ClipToBounds="True" Stroke="{StaticResource HighlightBrush}" StrokeThickness="1" Data="M 85.364473,6.9977109 6.0640998,86.29808 6.5333398,85.76586 M 6.9926698,7.4977169 86.293043,86.79809 85.760823,86.32885" />
</Grid>
</ControlTemplate>
</Button.Template>
</Button>
</Grid>
</Border>
<!--<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Foreground" Value="#ffffff" />
<Setter TargetName="PART_DeleteTagButton" Property="Visibility" Value="Visible" />
</Trigger>
</ControlTemplate.Triggers>-->
</ControlTemplate>
</Button.Template>
</Button>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="IsEditing" Value="True">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type local:EvernoteTagItem}">
<tkInput:AutoCompleteBox x:Name="PART_InputBox"
Text="{Binding Text, RelativeSource={RelativeSource TemplatedParent}, Mode=TwoWay}"
ItemsSource="{Binding AllTags, RelativeSource={RelativeSource AncestorType={x:Type local:EvernoteTagControl}}}"
IsTextCompletionEnabled="True"
/>
</ControlTemplate>
</Setter.Value>
</Setter>
</Trigger>
</Style.Triggers>
</Style>
I am getting these tags as:

Currently, you use a StackPanel as ItemsPanel, but a stack panel will never wrap its items in multiple dimensions. So instead, you should try panels like WrapPanel or UniformGrid
For the WrapPanel, you also need to set a Width in the ItemContainerStyle in order to assure same size for all tag items (according to your "what I want" picture).
Then you have to decide on the positioning of your PART_CreateTagButton button. With multi lines of tags, the grid layout of ItemsPresenter and PART_CreateTagButton might no longer be appropriate.
You can probably create a compound items source of the original tag items source and the button as last item. This way, the button will always be properly aligned with the tags. See Add extra items when using ItemsSource and How do you bind a CollectionContainer to a collection in a view model? for more details.

Changing background of TabControl

I would like to change the background color of a WPF TabControl:
Changing the background color of the TabControl does not work, because the Grid element (direct child of the TabControl) doesn't inherit the backround of its parent:
The code below works, but it changes the background color of all subsequent grids:
<TabControl>
<TabControl.Resources>
<Style TargetType="Grid">
<Setter Property="Background" Value="Green" />
</Style>
</TabControl.Resources>
<!-- ... -->
</TabControl>
Is there a more appropriate solution?

While writing answer, nkoniishvt has already given right idea in comments, but I anyway will finish posting complete example.
Add xmlns:s="clr-namespace:System;assembly=mscorlib" namespace in your control.
Add this ControlTemplate in your ResourceDictionary in xaml:
<ControlTemplate x:Key="CustomTabControlTemplate" TargetType="TabControl" >
<Grid ClipToBounds="True" SnapsToDevicePixels="True" KeyboardNavigation.TabNavigation="Local" >
<Grid.ColumnDefinitions>
<ColumnDefinition Name="ColumnDefinition0" />
<ColumnDefinition Width="0" Name="ColumnDefinition1" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" Name="RowDefinition0" />
<RowDefinition Height="*" Name="RowDefinition1" />
</Grid.RowDefinitions>
<TabPanel IsItemsHost="True" Name="HeaderPanel" Margin="2,2,2,0" Panel.ZIndex="1" KeyboardNavigation.TabIndex="1" Grid.Column="0" Grid.Row="0" Background="Aqua" />
<Border BorderThickness="{TemplateBinding Border.BorderThickness}" BorderBrush="{TemplateBinding Border.BorderBrush}" Background="{TemplateBinding Panel.Background}" Name="ContentPanel" KeyboardNavigation.TabIndex="2" KeyboardNavigation.TabNavigation="Local" KeyboardNavigation.DirectionalNavigation="Contained" Grid.Column="0" Grid.Row="1">
<ContentPresenter Content="{TemplateBinding TabControl.SelectedContent}" ContentTemplate="{TemplateBinding TabControl.SelectedContentTemplate}" ContentStringFormat="{TemplateBinding TabControl.SelectedContentStringFormat}" ContentSource="SelectedContent" Name="PART_SelectedContentHost" Margin="{TemplateBinding Control.Padding}" SnapsToDevicePixels="{TemplateBinding UIElement.SnapsToDevicePixels}" />
</Border>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="TabControl.TabStripPlacement">
<Setter Property="Grid.Row" TargetName="HeaderPanel">
<Setter.Value>
<s:Int32>1</s:Int32>
</Setter.Value>
</Setter>
<Setter Property="Grid.Row" TargetName="ContentPanel">
<Setter.Value>
<s:Int32>0</s:Int32>
</Setter.Value>
</Setter>
<Setter Property="RowDefinition.Height" TargetName="RowDefinition0">
<Setter.Value>
<GridLength>*</GridLength>
</Setter.Value>
</Setter>
<Setter Property="RowDefinition.Height" TargetName="RowDefinition1">
<Setter.Value>
<GridLength>Auto</GridLength>
</Setter.Value>
</Setter>
<Setter Property="FrameworkElement.Margin" TargetName="HeaderPanel">
<Setter.Value>
<Thickness>2,0,2,2</Thickness>
</Setter.Value>
</Setter>
<Trigger.Value>
<x:Static Member="Dock.Bottom" />
</Trigger.Value>
</Trigger>
<Trigger Property="TabControl.TabStripPlacement">
<Setter Property="Grid.Row" TargetName="HeaderPanel">
<Setter.Value>
<s:Int32>0</s:Int32>
</Setter.Value>
</Setter>
<Setter Property="Grid.Row" TargetName="ContentPanel">
<Setter.Value>
<s:Int32>0</s:Int32>
</Setter.Value>
</Setter>
<Setter Property="Grid.Column" TargetName="HeaderPanel">
<Setter.Value>
<s:Int32>0</s:Int32>
</Setter.Value>
</Setter>
<Setter Property="Grid.Column" TargetName="ContentPanel">
<Setter.Value>
<s:Int32>1</s:Int32>
</Setter.Value>
</Setter>
<Setter Property="ColumnDefinition.Width" TargetName="ColumnDefinition0">
<Setter.Value>
<GridLength>Auto</GridLength>
</Setter.Value>
</Setter>
<Setter Property="ColumnDefinition.Width" TargetName="ColumnDefinition1">
<Setter.Value>
<GridLength>*</GridLength>
</Setter.Value>
</Setter>
<Setter Property="RowDefinition.Height" TargetName="RowDefinition0">
<Setter.Value>
<GridLength>*</GridLength>
</Setter.Value>
</Setter>
<Setter Property="RowDefinition.Height" TargetName="RowDefinition1">
<Setter.Value>
<GridLength>0</GridLength>
</Setter.Value>
</Setter>
<Setter Property="FrameworkElement.Margin" TargetName="HeaderPanel">
<Setter.Value>
<Thickness>2,2,0,2</Thickness>
</Setter.Value>
</Setter>
<Trigger.Value>
<x:Static Member="Dock.Left" />
</Trigger.Value>
</Trigger>
<Trigger Property="TabControl.TabStripPlacement">
<Setter Property="Grid.Row" TargetName="HeaderPanel">
<Setter.Value>
<s:Int32>0</s:Int32>
</Setter.Value>
</Setter>
<Setter Property="Grid.Row" TargetName="ContentPanel">
<Setter.Value>
<s:Int32>0</s:Int32>
</Setter.Value>
</Setter>
<Setter Property="Grid.Column" TargetName="HeaderPanel">
<Setter.Value>
<s:Int32>1</s:Int32>
</Setter.Value>
</Setter>
<Setter Property="Grid.Column" TargetName="ContentPanel">
<Setter.Value>
<s:Int32>0</s:Int32>
</Setter.Value>
</Setter>
<Setter Property="ColumnDefinition.Width" TargetName="ColumnDefinition0">
<Setter.Value>
<GridLength>*</GridLength>
</Setter.Value>
</Setter>
<Setter Property="ColumnDefinition.Width" TargetName="ColumnDefinition1">
<Setter.Value>
<GridLength>Auto</GridLength>
</Setter.Value>
</Setter>
<Setter Property="RowDefinition.Height" TargetName="RowDefinition0">
<Setter.Value>
<GridLength>*</GridLength>
</Setter.Value>
</Setter>
<Setter Property="RowDefinition.Height" TargetName="RowDefinition1">
<Setter.Value>
<GridLength>0</GridLength>
</Setter.Value>
</Setter>
<Setter Property="FrameworkElement.Margin" TargetName="HeaderPanel">
<Setter.Value>
<Thickness>0,2,2,2</Thickness>
</Setter.Value>
</Setter>
<Trigger.Value>
<x:Static Member="Dock.Right" />
</Trigger.Value>
</Trigger>
<Trigger Property="UIElement.IsEnabled">
<Setter Property="TextElement.Foreground">
<Setter.Value>
<DynamicResource ResourceKey="{x:Static SystemColors.GrayTextBrushKey}" />
</Setter.Value>
</Setter>
<Trigger.Value>
<s:Boolean>False</s:Boolean>
</Trigger.Value>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
For example I set Background="Aqua" for TabPanel element inside root Grid.
Assign this ControlTemplate to the Template property of TabControl:
<TabControl Template="{StaticResource CustomTabControlTemplate}">
...
</TabControl>

How do I get a thicker drop shadow on my ToolTip?

I'm overriding my tooltips with the following:
<Style x:Key="{x:Type ToolTip}" TargetType="ToolTip">
<Setter Property="OverridesDefaultStyle" Value="True"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ToolTip">
<Grid>
<Grid.Background>
<SolidColorBrush />
</Grid.Background>
<mwt:SystemDropShadowChrome Color="#00FFFFFF" CornerRadius="5" Name="Shdw" SnapsToDevicePixels="True">
<Border CornerRadius="5">
<StackPanel>
<ContentPresenter TextBlock.Foreground="Black" />
</StackPanel>
</Border>
</mwt:SystemDropShadowChrome>
</Grid>
The Thickness value for the margin seems to have a maximum value of 5?
<ControlTemplate.Triggers>
<Trigger Property="ToolTipService.HasDropShadow">
<Setter Property="FrameworkElement.Margin" TargetName="Shdw">
<Setter.Value>
<Thickness>0,0,5,5</Thickness>
</Setter.Value>
</Setter>
<Trigger.Value>
<sys:Boolean>True</sys:Boolean>
</Trigger.Value>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
It would be nice to be able to see more of the dropshadow.
My bad for not posting all my code. Here it is with an edit based on the response from icebat:
<Style x:Key="{x:Type ToolTip}" TargetType="ToolTip">
<Setter Property="OverridesDefaultStyle" Value="True"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ToolTip">
<Grid>
<Grid.Background>
<SolidColorBrush />
</Grid.Background>
<mwt:SystemDropShadowChrome Color="#71000000" CornerRadius="5" Name="Shdw" SnapsToDevicePixels="True">
<Border CornerRadius="5">
<StackPanel>
<ContentPresenter TextOptions.TextRenderingMode="ClearType" TextOptions.TextFormattingMode="Display" TextBlock.FontFamily="Segoe UI" TextBlock.FontStretch="Normal" TextBlock.FontWeight="Normal" TextBlock.Foreground="Black" TextBlock.FontSize="13" Margin="18,8,16,4" HorizontalAlignment="Left" VerticalAlignment="Top" />
<Border HorizontalAlignment="Stretch" BorderThickness="0,1,0,0" BorderBrush="Gray" Margin="10,5,10,5" Grid.Column="0" Grid.Row="0" Grid.ColumnSpan="2">
<TextBlock Margin="8,4,0,0" FontWeight="Bold" Text="{x:Static res:AppStrings.Help_0_Footer}" FontSize="13" Foreground="#E3000000" />
</Border>
</StackPanel>
<Border.Background>
<LinearGradientBrush>
<LinearGradientBrush.StartPoint>
<Point X=".5" Y="0"/>
</LinearGradientBrush.StartPoint>
<LinearGradientBrush.EndPoint>
<Point X=".5" Y="1"/>
</LinearGradientBrush.EndPoint>
<LinearGradientBrush.GradientStops>
<GradientStop Color="#FFFFA200" Offset="1"/>
<GradientStop Color="White" Offset="0.305"/>
</LinearGradientBrush.GradientStops>
</LinearGradientBrush>
</Border.Background>
</Border>
</mwt:SystemDropShadowChrome>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="ToolTipService.HasDropShadow" Value="True">
<Setter Property="Margin" TargetName="Shdw" Value="0,0,5,5"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
I still don't get a thicker dropshadow for a margin larger than 5.

Margin is not limited. To see more of the shadow you need to apply margin not to the SystemDropShadowChrome decorator itself but to its content:
<mwt:SystemDropShadowChrome Name="Shdw" CornerRadius="5">
<Border Name="shdwContent" CornerRadius="5">
<StackPanel>
<ContentPresenter TextBlock.Foreground="Black" />
</StackPanel>
</Border>
</mwt:SystemDropShadowChrome>
...
<ControlTemplate.Triggers>
<Trigger Property="ToolTipService.HasDropShadow" Value="True">
<Setter Property="Margin" TargetName="ShdwContent" Value="0,0,5,5">
</Trigger>
</ControlTemplate.Triggers>
And as a side note, right now you are using transparent color as shadow color (#00FFFFFF). If that`s not changed with some triggers or by other means, you won`t see any shadow.

Dragging and dropping TreeViewItems in non-clickable area of TreeView [WPF]

A question about dragging and dropping tree view items in WPF.
My original question is a little complex. So I simplified it, and here is the code:
XAML
<Window x:Class="WpfApplication2.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="Window1" Height="300" Width="300">
<Grid>
<TreeView>
<TreeView.ItemContainerStyle>
<Style>
<Setter Property="TreeViewItem.IsExpanded" Value="True"/>
<Setter Property="TreeViewItem.Background" Value="LightBlue"/>
<Setter Property="TreeViewItem.AllowDrop" Value="True"/>
<EventSetter Event="TreeViewItem.MouseMove" Handler="TreeNode_MouseMove"/>
<EventSetter Event="TreeViewItem.Drop" Handler="TreeNode_Drop"/>
</Style>
</TreeView.ItemContainerStyle>
<TreeViewItem Header="first node in the tree"/>
<TreeViewItem Header="second node in the tree"></TreeViewItem>
<TreeViewItem Header="third node in the tree"></TreeViewItem>
</TreeView>
</Grid>
And code-behind:
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
}
private void TreeNode_MouseMove(object sender, MouseEventArgs e)
{
if (e.LeftButton == MouseButtonState.Pressed)
{
DragDrop.DoDragDrop(this, DateTime.Now.ToString(), DragDropEffects.Move);
}
}
private void TreeNode_Drop(object sender, DragEventArgs e)
{
string str = (string)e.Data.GetData(typeof(string));
MessageBox.Show(str);
}
}
So what I want to do is very simple, just pop up a message box when one tree view item is dragged and dropped on another tree view item.
When I drop it right on another item, it works fine, like this:
But if I drag it slightly off the boundary of the item, it does not work, like this:
The mouse cursor is displayed as a “forbidden sign”, sorry I can’t get it in the screen shot.
So now my question is: how to make the second condition work? How to make the Drop event still fire up when the dropping location is slightly off the boundary of the item?
Thanks in advance.

Take the default ControlTemplate of TreeViewItem and make the Border (the border which contains the ContentPresenter) to have a colspan of 2, e.g.:
<Border
BorderThickness="{TemplateBinding Border.BorderThickness}"
Padding="{TemplateBinding Control.Padding}"
BorderBrush="{TemplateBinding Border.BorderBrush}"
Background="{TemplateBinding Panel.Background}"
Name="Bd"
SnapsToDevicePixels="True"
Grid.Column="1" Grid.ColumnSpan="2">
Note that the whole area in TreeViewItem next to the TextBlock would become clickable. You may want to play around with the template to fit it to your needs.
Below is the ControlTemplate of TreeViewItem extracted using Dump Control Template Utility.
<?xml version="1.0" encoding="utf-16"?>
<ControlTemplate
TargetType="TreeViewItem" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition
Width="Auto"
MinWidth="19" />
<ColumnDefinition
Width="Auto" />
<ColumnDefinition
Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition
Height="Auto" />
<RowDefinition />
</Grid.RowDefinitions>
<ToggleButton
IsChecked="False"
ClickMode="Press"
Name="Expander">
<ToggleButton.Style>
<Style
TargetType="ToggleButton">
<Style.Resources>
<ResourceDictionary />
</Style.Resources>
<Setter
Property="UIElement.Focusable">
<Setter.Value>
<s:Boolean>False</s:Boolean>
</Setter.Value>
</Setter>
<Setter
Property="FrameworkElement.Width">
<Setter.Value>
<s:Double>19</s:Double>
</Setter.Value>
</Setter>
<Setter
Property="FrameworkElement.Height">
<Setter.Value>
<s:Double>13</s:Double>
</Setter.Value>
</Setter>
<Setter
Property="Control.Template">
<Setter.Value>
<ControlTemplate
TargetType="ToggleButton">
<Border
Background="#00FFFFFF"
Width="19"
Height="13">
<Border
BorderThickness="1,1,1,1"
CornerRadius="1,1,1,1"
BorderBrush="#FF7898B5"
Width="9"
Height="9"
SnapsToDevicePixels="True">
<Border.Background>
<LinearGradientBrush
StartPoint="0,0"
EndPoint="1,1">
<LinearGradientBrush.GradientStops>
<GradientStop
Color="#FFFFFFFF"
Offset="0.2" />
<GradientStop
Color="#FFC0B7A6"
Offset="1" />
</LinearGradientBrush.GradientStops>
</LinearGradientBrush>
</Border.Background>
<Path
Data="M0,2L0,3 2,3 2,5 3,5 3,3 5,3 5,2 3,2 3,0 2,0 2,2z"
Fill="#FF000000"
Name="ExpandPath"
Margin="1,1,1,1" />
</Border>
</Border>
<ControlTemplate.Triggers>
<Trigger
Property="ToggleButton.IsChecked">
<Setter
Property="Path.Data"
TargetName="ExpandPath">
<Setter.Value>
<StreamGeometry>M0,2L0,3 5,3 5,2z</StreamGeometry>
</Setter.Value>
</Setter>
<Trigger.Value>
<s:Boolean>True</s:Boolean>
</Trigger.Value>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ToggleButton.Style>
</ToggleButton>
<Border
BorderThickness="{TemplateBinding Border.BorderThickness}"
Padding="{TemplateBinding Control.Padding}"
BorderBrush="{TemplateBinding Border.BorderBrush}"
Background="{TemplateBinding Panel.Background}"
Name="Bd"
SnapsToDevicePixels="True"
Grid.Column="1">
<ContentPresenter
Content="{TemplateBinding HeaderedContentControl.Header}"
ContentTemplate="{TemplateBinding HeaderedContentControl.HeaderTemplate}"
ContentStringFormat="{TemplateBinding HeaderedItemsControl.HeaderStringFormat}"
ContentSource="Header"
Name="PART_Header"
HorizontalAlignment="{TemplateBinding Control.HorizontalContentAlignment}"
SnapsToDevicePixels="{TemplateBinding UIElement.SnapsToDevicePixels}" />
</Border>
<ItemsPresenter
Name="ItemsHost"
Grid.Column="1"
Grid.Row="1"
Grid.ColumnSpan="2" />
</Grid>
<ControlTemplate.Triggers>
<Trigger
Property="TreeViewItem.IsExpanded">
<Setter
Property="UIElement.Visibility"
TargetName="ItemsHost">
<Setter.Value>
<x:Static
Member="Visibility.Collapsed" />
</Setter.Value>
</Setter>
<Trigger.Value>
<s:Boolean>False</s:Boolean>
</Trigger.Value>
</Trigger>
<Trigger
Property="ItemsControl.HasItems">
<Setter
Property="UIElement.Visibility"
TargetName="Expander">
<Setter.Value>
<x:Static
Member="Visibility.Hidden" />
</Setter.Value>
</Setter>
<Trigger.Value>
<s:Boolean>False</s:Boolean>
</Trigger.Value>
</Trigger>
<Trigger
Property="TreeViewItem.IsSelected">
<Setter
Property="Panel.Background"
TargetName="Bd">
<Setter.Value>
<DynamicResource
ResourceKey="{x:Static SystemColors.HighlightBrushKey}" />
</Setter.Value>
</Setter>
<Setter
Property="TextElement.Foreground">
<Setter.Value>
<DynamicResource
ResourceKey="{x:Static SystemColors.HighlightTextBrushKey}" />
</Setter.Value>
</Setter>
<Trigger.Value>
<s:Boolean>True</s:Boolean>
</Trigger.Value>
</Trigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition
Property="TreeViewItem.IsSelected">
<Condition.Value>
<s:Boolean>True</s:Boolean>
</Condition.Value>
</Condition>
<Condition
Property="Selector.IsSelectionActive">
<Condition.Value>
<s:Boolean>False</s:Boolean>
</Condition.Value>
</Condition>
</MultiTrigger.Conditions>
<Setter
Property="Panel.Background"
TargetName="Bd">
<Setter.Value>
<DynamicResource
ResourceKey="{x:Static SystemColors.ControlBrushKey}" />
</Setter.Value>
</Setter>
<Setter
Property="TextElement.Foreground">
<Setter.Value>
<DynamicResource
ResourceKey="{x:Static SystemColors.ControlTextBrushKey}" />
</Setter.Value>
</Setter>
</MultiTrigger>
<Trigger
Property="UIElement.IsEnabled">
<Setter
Property="TextElement.Foreground">
<Setter.Value>
<DynamicResource
ResourceKey="{x:Static SystemColors.GrayTextBrushKey}" />
</Setter.Value>
</Setter>
<Trigger.Value>
<s:Boolean>False</s:Boolean>
</Trigger.Value>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>

use AllowDrop property and Drop event for TreeView itself.
this is from msdn: http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/4b8bafe5-ae3e-439d-953a-f534a60dbb2d/

Styling a TextBox with IDataErrorInfo in WPF

I'm trying to change style a text box. By now, I have made that my textbox shows an asterisc on the right of its border with this code:
<Style TargetType="{x:Type TextBox}">
<Setter Property="Validation.ErrorTemplate">
<Setter.Value>
<ControlTemplate>
<Grid>
<TextBlock DockPanel.Dock="Right" HorizontalAlignment="Right" Foreground="Red" FontSize="14pt" FontWeight="Bold" Text="*"></TextBlock>
<Border BorderBrush="Red" BorderThickness="1">
<AdornedElementPlaceholder Name="controlWithError"/>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true">
<Setter Property="ToolTip" Value="{Binding Path=(Validation.Errors)[0].ErrorContent}"/>
</Trigger>
</Style.Triggers>
</Style>
But I'd like my textbox be shown with a red triangle on the right upper corner. How could I get this style on my textbox?
Thanks.

I have already done what I wanted, it was just like this:
<Style TargetType="{x:Type TextBox}">
<Setter Property="Validation.ErrorTemplate">
<Setter.Value>
<ControlTemplate>
<Grid>
<Polygon Points="0,0 10,0 0,10 0,0" HorizontalAlignment="Right" Fill="Red" FlowDirection="RightToLeft"></Polygon>
<Border BorderBrush="Red" BorderThickness="1">
<AdornedElementPlaceholder Name="controlWithError" />
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true">
<Setter Property="ToolTip" Value="{Binding RelativeSource={x:Static RelativeSource.Self}, Path=(Validation.Errors)[0].ErrorContent}"/>
</Trigger>
</Style.Triggers>
</Style>