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Change ComboBoxItem Background when Mouse Is Over - WPF

I am using the WPF extended library WatermarkedComboBox and when I hover over a ComboBoxItem I want the background to change to a light grey and not the defaul blue.
<!-- Combo Box -->
<xctk:WatermarkComboBox Style="{StaticResource MonthComboBoxDropDown}" ItemsSource="{Binding ListOfMonths}" SelectedItem="{Binding SelectedMonth, ValidatesOnDataErrors=True}" Margin="0,0,20,0">
<xctk:WatermarkComboBox.Watermark>
<TextBlock Text="Month" Foreground="{StaticResource OffsetWhiteBrush}"/>
</xctk:WatermarkComboBox.Watermark>
<xctk:WatermarkComboBox.Resources>
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="Pink" />
</xctk:WatermarkComboBox.Resources>
<xctk:WatermarkComboBox.ItemContainerStyle>
<Style TargetType="{x:Type ComboBoxItem}">
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Background" Value="Pink" />
<Setter Property="Foreground" Value="Yellow" />
<Setter Property="BorderThickness" Value="5" />
</Trigger>
</Style.Triggers>
</Style>
</xctk:WatermarkComboBox.ItemContainerStyle>
</xctk:WatermarkComboBox>
<!-- Combo box styling -->
<Style x:Key="MonthComboBoxDropDown" TargetType="{x:Type ComboBox}" BasedOn="{StaticResource TextBoxErrorStyle}">
<Setter Property="Foreground" Value="{StaticResource WhiteColorBrush}" />
<Setter Property="FontSize" Value="{StaticResource FontSize20}" />
<Setter Property="FontFamily" Value="{StaticResource LatoRegular}" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<ToggleButton Grid.Column="2" Focusable="false" IsChecked="{Binding Path=IsDropDownOpen,Mode=TwoWay,RelativeSource={RelativeSource TemplatedParent}}" >
<ToggleButton.Template>
<ControlTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="5*" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Border Name="Border" Grid.ColumnSpan="2" Background="{StaticResource DarkGreyBrush}" BorderThickness="0" />
<Path x:Name="Arrow" Grid.Column="1" Fill="{StaticResource WhiteColorBrush}" HorizontalAlignment="Center" VerticalAlignment="Center" Data="M 0 0 L 4 4 L 8 0 Z"/>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="ToggleButton.IsChecked" Value="true">
<Setter TargetName="Border" Property="Background" Value="{StaticResource LightGreyBrush}" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</ToggleButton.Template>
</ToggleButton>
<ContentPresenter Name="ContentSite" IsHitTestVisible="False" Content="{TemplateBinding SelectionBoxItem}" ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}" ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}" Margin="3" />
<TextBox x:Name="PART_EditableTextBox" Visibility="Hidden" MinWidth="120" />
<Popup Name="Popup" Placement="Bottom" IsOpen="{TemplateBinding IsDropDownOpen}" AllowsTransparency="True" Focusable="False" PopupAnimation="Slide">
<Grid Name="DropDown" SnapsToDevicePixels="True" MinWidth="{TemplateBinding ActualWidth}" MaxHeight="{TemplateBinding MaxDropDownHeight}">
<Border x:Name="DropDownBorder" Background="{StaticResource DarkGreyBrush}" />
<ScrollViewer SnapsToDevicePixels="True" Foreground="{StaticResource WhiteColorBrush}" FontFamily="{StaticResource LatoRegular}" FontSize="{StaticResource FontSize20}" VerticalAlignment="Center">
<StackPanel IsItemsHost="True" />
</ScrollViewer>
</Grid>
</Popup>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
When I hover over the an item in the combo box it looks like this
I have managed to make the foreground and border change but how can I also make the background change?

Add to your ComboBox style to change the HighlightBrush to gray
<Style x:Key="MonthComboBoxDropDown" TargetType="{x:Type ComboBox}" BasedOn=" {StaticResource TextBoxErrorStyle}">
<Style.Resources>
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="Gray"/>
<SolidColorBrush x:Key="{x:Static SystemColors.InactiveSelectionHighlightBrushKey}" Color="DarkGray"/>
</Style.Resources>
<Setter Property="Foreground" Value="{StaticResource WhiteColorBrush}" />
<Setter Property="FontSize" Value="{StaticResource FontSize20}" />
<Setter Property="FontFamily" Value="{StaticResource LatoRegular}" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<ToggleButton Grid.Column="2" Focusable="false" IsChecked="{Binding Path=IsDropDownOpen,Mode=TwoWay,RelativeSource={RelativeSource TemplatedParent}}" >
<ToggleButton.Template>
<ControlTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="5*" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Border Name="Border" Grid.ColumnSpan="2" Background="{StaticResource DarkGreyBrush}" BorderThickness="0" />
<Path x:Name="Arrow" Grid.Column="1" Fill="{StaticResource WhiteColorBrush}" HorizontalAlignment="Center" VerticalAlignment="Center" Data="M 0 0 L 4 4 L 8 0 Z"/>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="ToggleButton.IsChecked" Value="true">
<Setter TargetName="Border" Property="Background" Value="{StaticResource LightGreyBrush}" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</ToggleButton.Template>
</ToggleButton>
<ContentPresenter Name="ContentSite" IsHitTestVisible="False" Content="{TemplateBinding SelectionBoxItem}" ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}" ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}" Margin="3" />
<TextBox x:Name="PART_EditableTextBox" Visibility="Hidden" MinWidth="120" />
<Popup Name="Popup" Placement="Bottom" IsOpen="{TemplateBinding IsDropDownOpen}" AllowsTransparency="True" Focusable="False" PopupAnimation="Slide">
<Grid Name="DropDown" SnapsToDevicePixels="True" MinWidth="{TemplateBinding ActualWidth}" MaxHeight="{TemplateBinding MaxDropDownHeight}">
<Border x:Name="DropDownBorder" Background="{StaticResource DarkGreyBrush}" />
<ScrollViewer SnapsToDevicePixels="True" Foreground="{StaticResource WhiteColorBrush}" FontFamily="{StaticResource LatoRegular}" FontSize="{StaticResource FontSize20}" VerticalAlignment="Center">
<StackPanel IsItemsHost="True" />
</ScrollViewer>
</Grid>
</Popup>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>

<Style x:Key="ComboBox" TargetType="{x:Type ComboBoxItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBoxItem}">
<Border x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="True">
<ContentPresenter ContentTemplate="{TemplateBinding ContentTemplate}" Content="{TemplateBinding Content}" ContentStringFormat="{TemplateBinding ContentStringFormat}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="TextElement.Foreground" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
</Trigger>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Background" TargetName="Bd" Value="{StaticResource LightGreyBrush}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
To override the style I had to override the ComboBoxItem ControlTemplate.

C# WPF ComboBox with rounded corners IsMouseOver won't work

I found this code on doing rounded corners on combobox, I have modifyed it a little, but I have two Issues:
1) The mouseover on the combobox (textbox + togglebutton) won't
work. (I want the standard bahavior with blue background on mouseover, put red just to see if something happend)
2) when I click on the togglebutton I get the popup, but how can I make the textbox clickable to get the popup?
This is what I get:
This is what I want when mouseover (but with rounded corner)
Here are the code:
<Style x:Key="BorderStyle">
<Setter Property="Control.BorderBrush" Value="#A0A1A2" />
<Setter Property="Control.BorderThickness" Value="1" />
<Setter Property="Control.Background" Value="Transparent" />
<Setter Property="Control.Foreground" Value="#101010" />
<Setter Property="Control.FontFamily" Value="Arial" />
<Setter Property="Control.FontWeight" Value="Normal" />
<Setter Property="Control.FontStretch" Value="Normal" />
<Setter Property="Control.FontStyle" Value="Normal" />
</Style>
<Style x:Key="ComboBoxTextBoxStyle" TargetType="{x:Type TextBox}">
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="true">
<Setter Property="Background" Value="Red" />
</Trigger>
</Style.Triggers>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TextBox}">
<Grid>
<Border CornerRadius="2,0,0,2"
BorderThickness="1,1,0,1"
Background="{TemplateBinding Background}"
BorderBrush="#A0A1A2">
<ScrollViewer x:Name="PART_ContentHost"/>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="ComboBoxButtonStyle" TargetType="{x:Type ToggleButton}">
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="true">
<Setter Property="Background" Value="Red" />
</Trigger>
</Style.Triggers>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ToggleButton}">
<Border Background="#EAEAEA"
x:Name="border"
CornerRadius="0,2,2,0"
BorderThickness="0,1,1,1"
BorderBrush="#A0A1A2">
<ContentPresenter />
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="RoundComboBox" TargetType="{x:Type ComboBox}" BasedOn="{StaticResource BorderStyle}">
<Setter Property="HorizontalContentAlignment" Value="Left"/>
<Setter Property="VerticalContentAlignment" Value="Center"/>
<Setter Property="FontSize" Value="14px"/>
<Setter Property="IsReadOnly" Value="True"/>
<Setter Property="Height" Value="25"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition MaxWidth="18"/>
</Grid.ColumnDefinitions>
<TextBox Name="PART_EditableTextBox"
Padding="0,0,0,0"
IsHitTestVisible="False"
Height="{TemplateBinding Height}"
BorderBrush="#A0A1A2"
Background="#EAEAEA"
Style="{StaticResource ComboBoxTextBoxStyle}"/>
<ToggleButton Grid.Column="1"
Height="{TemplateBinding Height}"
Style="{StaticResource ComboBoxButtonStyle}"
Focusable="False"
IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"
ClickMode="Press">
<Path Grid.Column="1"
HorizontalAlignment="Center"
VerticalAlignment="Center"
Data="M 0 0 L 4 4 L 8 0 Z"
Fill="Black" />
</ToggleButton>
<ContentPresenter Grid.Column="0"
Name="ContentSite"
Content="{TemplateBinding SelectionBoxItem}"
ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
VerticalAlignment="Center"
HorizontalAlignment="Left"
Margin="6,0,0,0"/>
<Popup Grid.Column="0"
Name="Popup"
Placement="Bottom"
IsOpen="{TemplateBinding IsDropDownOpen}"
AllowsTransparency="True"
Focusable="False"
PopupAnimation="Slide">
<Grid Name="DropDown"
SnapsToDevicePixels="True"
MinWidth="{TemplateBinding ActualWidth}"
MaxHeight="{TemplateBinding MaxDropDownHeight}">
<Border x:Name="DropDownBorder"
BorderThickness="1"
CornerRadius="2"
Background="White"
BorderBrush="#A0A1A2"/>
<ScrollViewer SnapsToDevicePixels="True">
<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" />
</ScrollViewer>
</Grid>
</Popup>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>

There were a few problems here. Each item I changed in the XAML is commented.
I've also removed the IsMouseOver triggers from the togglebutton and textbox styles, and put it in the ComboBox style. It now sets the background for the whole combobox when the mouse is anywhere over the ComboBox. The two controls in the ComboBox template now have Background="{TemplateBinding Background}", so they'll use the background color set by that trigger.
I've restored IsHitTestVisible on the textbox, but used a TemplateBinding to bind it to the ComboBox's IsEditable property. This will give you the correct mouse pointer over the textbox.
<!--
Better to define this in one place.
I'd do the same with the border color that you use everywhere.
-->
<SolidColorBrush x:Key="ComboBackgroundBrush" Color="#EAEAEA" />
<Style x:Key="ComboBoxTextBoxStyle" TargetType="{x:Type TextBox}">
<!--
Must set this in a setter, not an an attribute on the control instance.
The attribute you had will override anything the style does. This is part of
"dependency property value precedence".
-->
<Setter Property="Background" Value="{StaticResource ComboBackgroundBrush}" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TextBox}">
<Grid>
<Border CornerRadius="2,0,0,2"
BorderThickness="1,1,0,1"
Background="{TemplateBinding Background}"
BorderBrush="#A0A1A2"
>
<ScrollViewer x:Name="PART_ContentHost"/>
</Border>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="ComboBoxButtonStyle" TargetType="{x:Type ToggleButton}">
<Setter Property="Background" Value="{StaticResource ComboBackgroundBrush}" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ToggleButton}">
<!--
Needs {TemplateBinding Background} so it uses whatever background brush
the control has at any given moment.
-->
<Border Background="{TemplateBinding Background}"
x:Name="border"
CornerRadius="0,2,2,0"
BorderThickness="0,1,1,1"
BorderBrush="#A0A1A2">
<ContentPresenter />
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="ComboBoxOverlayToggleButtonStyle" TargetType="ToggleButton">
<Setter Property="Focusable" Value="False" />
<Setter Property="ClickMode" Value="Press" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ToggleButton">
<Grid Background="Transparent" />
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="RoundComboBox" TargetType="{x:Type ComboBox}" BasedOn="{StaticResource BorderStyle}">
<Setter Property="HorizontalContentAlignment" Value="Left"/>
<Setter Property="VerticalContentAlignment" Value="Center"/>
<Setter Property="FontSize" Value="14px"/>
<Setter Property="IsReadOnly" Value="True"/>
<Setter Property="Height" Value="25"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition MaxWidth="18"/>
</Grid.ColumnDefinitions>
<ToggleButton
Grid.Column="0"
Style="{StaticResource ComboBoxOverlayToggleButtonStyle}"
IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"
/>
<!--
Two problems:
1. IsHitTestVisible="False" prevented it from getting any mouse messages.
2. Background attribute was overriding anything the Style did,
so even if the trigger had fired, its setter would have failed.
Also, Height="{TemplateBinding Height}" is unnecessary. It'll size to its parent Grid.
And BorderBrush="#A0A1A2" should probably be in the Style
-->
<TextBox Name="PART_EditableTextBox"
Padding="0,0,0,0"
BorderBrush="#A0A1A2"
Style="{StaticResource ComboBoxTextBoxStyle}"
Background="{TemplateBinding Background}"
IsHitTestVisible="{TemplateBinding IsEditable}"
/>
<ToggleButton Grid.Column="1"
Height="{TemplateBinding Height}"
Style="{StaticResource ComboBoxButtonStyle}"
Focusable="False"
IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"
ClickMode="Press"
Background="{TemplateBinding Background}"
>
<Path Grid.Column="1"
HorizontalAlignment="Center"
VerticalAlignment="Center"
Data="M 0 0 L 4 4 L 8 0 Z"
Fill="Black" />
</ToggleButton>
<ContentPresenter Grid.Column="0"
Name="ContentSite"
Content="{TemplateBinding SelectionBoxItem}"
ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
VerticalAlignment="Center"
HorizontalAlignment="Left"
Margin="6,0,0,0"
/>
<Popup Grid.Column="0"
Name="Popup"
Placement="Bottom"
IsOpen="{TemplateBinding IsDropDownOpen}"
AllowsTransparency="True"
Focusable="False"
PopupAnimation="Slide">
<Grid Name="DropDown"
SnapsToDevicePixels="True"
MinWidth="{TemplateBinding ActualWidth}"
MaxHeight="{TemplateBinding MaxDropDownHeight}">
<Border x:Name="DropDownBorder"
BorderThickness="1"
CornerRadius="2"
Background="White"
BorderBrush="#A0A1A2"/>
<ScrollViewer SnapsToDevicePixels="True">
<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" />
</ScrollViewer>
</Grid>
</Popup>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="true">
<Setter Property="Background" Value="Red" />
</Trigger>
</Style.Triggers>
</Style>

Combobox assigning of selecteditem not displaying wpf

I have a dynamic combobox items added to it. When i select item, it displays properly. but when reloading the control i am assigning selected item to the combobox but it is not displaying.
simpleComboBox.SelectedIndex = simpleComboBox.Items.IndexOf(SelectedItem);
It showing correct index value but values are not displaying.
<Style x:Key="ComboBoxStyle" TargetType="{x:Type ComboBox}">
<Setter Property="Margin" Value="10"/>
<Setter Property="Foreground" Value="{StaticResource ForegroundTextNormalBrush}" />
<Setter Property="FontFamily" Value="{StaticResource TextFontFamily}"/>
<Setter Property="FontSize" Value="{StaticResource FontSize16}"/>
<Setter Property="Background" Value="{StaticResource ControlBackgroundBrush}"/>
<Setter Property="BorderBrush" Value="{StaticResource BorderColorBrush}"/>
<Setter Property="IsEditable" Value="True"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="50"/>
</Grid.ColumnDefinitions>
<TextBox Name="PART_EditableTextBox"
Style="{StaticResource ComboBoxTextBoxStyle}"
Height="{TemplateBinding Height}"/>
<ToggleButton Grid.Column="1" Margin="0" Style="{StaticResource ToggleButtonStyle}"
Focusable="False"
IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"
ClickMode="Press">
<TextBlock Grid.Column="1" Style="{StaticResource ToggleButtonTextBlockStyle}"/>
</ToggleButton>
<ContentPresenter Name="ContentSite"
ContentTemplate="{TemplateBinding SelectionBoxItemTemplate}"
Content="{TemplateBinding SelectionBoxItem}"
ContentStringFormat="{TemplateBinding SelectionBoxItemStringFormat}"
ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}"
VerticalAlignment="Center"
HorizontalAlignment="Left"
Margin="5,0,0,0"/>
<Popup Name="Popup"
Placement="Bottom"
IsOpen="{TemplateBinding IsDropDownOpen}"
AllowsTransparency="True"
Focusable="False"
PopupAnimation="Fade">
<Grid Name="DropDown"
SnapsToDevicePixels="True"
MinWidth="{TemplateBinding ActualWidth}"
MaxHeight="{TemplateBinding MaxDropDownHeight}">
<Border
x:Name="DropDownBorder"
BorderThickness="3"
CornerRadius="5"
Background="{StaticResource AddControlTextBoxBackgroundBrush}"
BorderBrush="{StaticResource AddControlInnerBorderBrush}"/>
<ScrollViewer Margin="4,6,4,6" SnapsToDevicePixels="True">
<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" />
</ScrollViewer>
</Grid>
</Popup>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
<Setter Property="ItemTemplate">
<Setter.Value>
<DataTemplate >
<TextBlock Style="{StaticResource SelectedTextBlockStyle}" Text="{Binding}" />
</DataTemplate>
</Setter.Value>
</Setter>
<Setter Property="ItemContainerStyle">
<Setter.Value>
<Style TargetType="ComboBoxItem">
<Setter Property="Foreground" Value="{StaticResource ForegroundTextNormalBrush}" />
<Setter Property="FontFamily" Value="{StaticResource ArialFontFamily}"/>
<Setter Property="FontSize" Value="24"/>
<Setter Property="BorderThickness" Value="0"/>
</Style>
</Setter.Value>
</Setter>
</Style>

Try setting
simpleComboBox.SelectedItem = SelectedItem;
and also set IsSynchronizedWithCurrentItem="True".
This will solve your issue.

CheckComboBox : How to prevent a combobox from closing after a selection is clicked?

I've got a combobox and it's populated with a bunch of checkboxes. I wish the user to be able to click multiple times before the combobox closes (or is closed by the user themselves). The problems right now is that each time a checkbox is clicked, the combobox closes, forcing the user who wants to select multiple options to re-open it several times.
I've found other questions on the same subject but those apply to Silverlight, Qt etc. comparing the tags.
I've tried setting StayOpenOnEdit but that didn't do the trick. As far I could see, there's no property addressing my issue. That creates a suspicion that I might be barning up the wrong component all together.
How do I prevent the combobox to close automatically after a click in a checkbox in it?
Is there a more suitable component for such task and, if so, what's its name?
Please note that even if the answer to #2 is "yes", I'm still curious of #1 for purely academic reasons.
I've played with toggle button and list box, as someone suggested in a post. However, the that led only to an always fully shown list of all the checkboxes with some greyish thing behind it (which I'm assuming is the toggler). Perhaps I did something less clever in the mark-up.
<ToggleButton HorizontalAlignment="Left"
Margin="550,62,0,0"
VerticalAlignment="Top"
Width="100">
<ListBox x:Name="listBox1"
HorizontalAlignment="Left"
Height="100"
VerticalAlignment="Top" Width="100">
<CheckBox x:Name="checkBox3" Content="CheckBox"/>
<CheckBox x:Name="checkBox4" Content="CheckBox"/>
</ListBox>
</ToggleButton>
The point is to achieve something like this but it needs to be a standard WPF control (the concatenated line of all selected items is nice but not a must). Also, I've read the complaints that the binding and handling is not fully developed yet and I feel a bit suspicious.

Using Exapander Control you can achieve multple item selection without closing popup after single selection.
For understanding please run this code separately.
xaml
<Window.Resources>
<ControlTemplate x:Key="ComboboxToggleButton" TargetType="{x:Type ToggleButton}">
<Grid Background="{Binding Background,RelativeSource={RelativeSource AncestorType={x:Type ComboBox}}}">
<Grid.ColumnDefinitions>
<ColumnDefinition />
<ColumnDefinition Width="35" />
</Grid.ColumnDefinitions>
<Border x:Name="Border" Grid.ColumnSpan="2" Background="Transparent" BorderBrush="Black" BorderThickness="{Binding BorderThickness,RelativeSource={RelativeSource TemplatedParent}}"/>
<Path x:Name="Arrow" Grid.Column="1" Opacity="1" Stroke="Black" StrokeThickness="1.5" HorizontalAlignment="Center" VerticalAlignment="Center" Data="M 0 0 L 6 6 L 12 0" />
<Path x:Name="Arrow_checked" Opacity="0" Grid.Column="1" Fill="Black" Stroke="Black" StrokeThickness="1" HorizontalAlignment="Center" VerticalAlignment="Center" Data="M 0 0 L 6 6 L 12 0 Z" />
<ContentPresenter TextElement.FontFamily="Segoe Ui Dark" TextElement.FontSize="18" TextElement.Foreground="Black" VerticalAlignment="Center" Grid.Column="0" Margin="10,0,0,0" HorizontalAlignment="Left" RecognizesAccessKey="True" SnapsToDevicePixels="True" />
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="ToggleButton.IsMouseOver" Value="true">
<Setter TargetName="Border" Property="Background" Value="Gray" />
<Setter TargetName="Border" Property="BorderThickness" Value="1.2" />
</Trigger>
<Trigger Property="IsChecked" Value="False">
<Setter Property="Opacity" Value="1" TargetName="Arrow"/>
<Setter Property="Opacity" Value="0" TargetName="Arrow_checked"/>
</Trigger>
<Trigger Property="ToggleButton.IsChecked" Value="true">
<Setter Property="Opacity" Value="0" TargetName="Arrow"/>
<Setter Property="Opacity" Value="1" TargetName="Arrow_checked"/>
</Trigger>
<Trigger Property="IsEnabled" Value="False">
<Setter TargetName="Border" Property="Background" Value="Gray" />
<Setter TargetName="Border" Property="BorderBrush" Value="White" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
<Style TargetType="{x:Type Expander}">
<Setter Property="FontFamily" Value="Segoe Ui Dark"></Setter>
<Setter Property="HorizontalContentAlignment" Value="Stretch"/>
<Setter Property="VerticalContentAlignment" Value="Stretch"/>
<Setter Property="MaxHeight" Value="200"></Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Expander}">
<DockPanel>
<ToggleButton x:Name="HeaderSite" Height="35" Background="{TemplateBinding Background}" ContentTemplate="{TemplateBinding HeaderTemplate}" ContentTemplateSelector="{TemplateBinding HeaderTemplateSelector}" Content="{TemplateBinding Header}" DockPanel.Dock="Top" Foreground="Black" FontStyle="{TemplateBinding FontStyle}" FontFamily="Segoe UI Dark"
IsChecked="{Binding IsExpanded, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Template="{StaticResource ComboboxToggleButton}" />
<Border BorderThickness="0,4.5,0,0" BorderBrush="Transparent">
<Border x:Name="bod" BorderBrush="Transparent" SnapsToDevicePixels="True" BorderThickness="1">
<ContentPresenter x:Name="ExpandSite" Focusable="false" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Visibility="Collapsed" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" />
</Border>
</Border>
</DockPanel>
<ControlTemplate.Triggers>
<Trigger Property="IsExpanded" Value="true">
<Setter Property="Visibility" TargetName="ExpandSite" Value="Visible"/>
<Setter Property="BorderBrush" TargetName="bod" Value="Black"/>
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="Gray"></Setter>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style x:Key="itemstyle" TargetType="{x:Type ListBoxItem}">
<Setter Property="SnapsToDevicePixels" Value="true" />
<Setter Property="OverridesDefaultStyle" Value="true" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ListBoxItem">
<Grid x:Name="Border" Height="40" SnapsToDevicePixels="true">
<Grid.Background>
<SolidColorBrush Color="Transparent" />
</Grid.Background>
<ContentPresenter Name="cmb_name" TextElement.FontFamily="Segoe Ui Dark" TextElement.FontSize="18" TextElement.Foreground="Black" Margin="10,0,0,0" VerticalAlignment="Center"></ContentPresenter>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter TargetName="Border" Property="Background" Value="Gray"></Setter>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Setter Property="FocusVisualStyle">
<Setter.Value>
<Style TargetType="Control">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate>
<Border BorderBrush="{DynamicResource customBlueBrush}" BorderThickness="1" Margin="1,2,2,2" >
<Rectangle Fill="{DynamicResource customBlueBrush}" Opacity="0.1"></Rectangle>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Setter.Value>
</Setter>
</Style>
<Style TargetType="CheckBox" >
<Setter Property="SnapsToDevicePixels" Value="True"></Setter>
<Setter Property="OverridesDefaultStyle" Value="True"></Setter>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="CheckBox">
<Grid x:Name="ab" Background="Transparent">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="30"/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Rectangle VerticalAlignment="Center" Height="20" Width="20" Fill="White" HorizontalAlignment="Left"></Rectangle>
<Grid x:Name="checkGrid" VerticalAlignment="Center" Height="20" Width="20" Background="Black" HorizontalAlignment="Left">
<Viewbox Height="13" Width="13">
<Path x:Name="Check" SnapsToDevicePixels="True" UseLayoutRounding="True" Width="18.7969" Height="16.3094" Canvas.Left="0" Canvas.Top="1.52588e-005" Stretch="Fill" Fill="White" Data="F1 M 0.731262,8.75935L 0.106262,8.08437C 0.0354614,7.9948 0,7.8979 0,7.79375C 0,7.66875 0.0479736,7.5573 0.143799,7.45937L 1.94067,5.77187C 2.02606,5.69893 2.12708,5.66249 2.24377,5.66249C 2.30212,5.66249 2.36096,5.67397 2.42035,5.69685C 2.47974,5.71977 2.52814,5.75417 2.56567,5.79997L 7.5188,11.1406L 16.0438,0.165604C 16.1417,0.055191 16.2584,1.52588e-005 16.3938,1.52588e-005C 16.4979,1.52588e-005 16.5896,0.0322723 16.6688,0.0968475L 18.6313,1.60939C 18.6709,1.64272 18.7084,1.69011 18.7438,1.75154C 18.7792,1.813 18.7969,1.8698 18.7969,1.92189C 18.7969,2.03435 18.7646,2.1385 18.7,2.23439L 7.74377,16.3094L 0.731262,8.75935 Z " />
</Viewbox>
</Grid>
<Grid Background="Transparent" Grid.Column="1" IsHitTestVisible="True" HorizontalAlignment="Stretch">
<TextBlock VerticalAlignment="Center" FontSize="18" FontFamily="Segoe Ui Dark" Foreground="Black" TextTrimming="CharacterEllipsis">
<ContentPresenter></ContentPresenter>
</TextBlock>
</Grid>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsChecked" Value="True">
<Setter Property="Opacity" Value="1" TargetName="Check"></Setter>
</Trigger>
<Trigger Property="IsChecked" Value="False">
<Setter Property="Opacity" Value="0" TargetName="Check"></Setter>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Setter Property="FocusVisualStyle">
<Setter.Value>
<Style TargetType="Control">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate>
<Border BorderBrush="{DynamicResource customBlueBrush}" SnapsToDevicePixels="True" BorderThickness="1" Margin="-5,1,3,1" />
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Setter.Value>
</Setter>
</Style>
</Window.Resources>
<Grid x:Name="gd" >
<Expander Width="500">
<Expander.Header>
<ListBox Background="Transparent" IsHitTestVisible="False" BorderBrush="Transparent" ScrollViewer.HorizontalScrollBarVisibility="Hidden" ScrollViewer.VerticalScrollBarVisibility="Disabled" BorderThickness="0" ItemsSource="{Binding ElementName=lst,Path=SelectedItems}">
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<WrapPanel Orientation="Horizontal"></WrapPanel>
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding ContentData}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Expander.Header>
<Expander.Content>
<ListBox Background="Transparent" ItemContainerStyle="{StaticResource itemstyle}" HorizontalContentAlignment="Stretch" x:Name="lst" SelectionMode="Multiple">
<ListBox.ItemTemplate>
<DataTemplate>
<CheckBox x:Name="checkBox" IsChecked="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListBoxItem}}, Path=IsSelected}" Content="{Binding ContentData}"></CheckBox>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Expander.Content>
</Expander>
</Grid>
c# code
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
ObservableCollection<Customer> custdata = new ObservableCollection<Customer>();
custdata.Add(new Customer() { ContentData = "content1" });
custdata.Add(new Customer() { ContentData = "content2" });
custdata.Add(new Customer() { ContentData = "content3" });
custdata.Add(new Customer() { ContentData = "content4" });
custdata.Add(new Customer() { ContentData = "content5" });
custdata.Add(new Customer() { ContentData = "content6" });
lst.ItemsSource = custdata;
}
}
public class Customer
{
public string ContentData { get; set; }
}
Result

Konrad,
I also decided to use a ComboBox in this manner, because the code was just dead simple. The easiest way I have found to keep the ComboBox popup open is to wire-up to the PreviewMouseDown event of the control in the ComboBox's item template. handle the behavior yourself, and then mark the mouse event handled. Works great for me. In the sample below, each object in FilterItems is a simple view model with a Text property and an IsChecked property.
<ComboBox IsEditable="True" IsReadOnly="False" ItemsSource="{Binding FilterItems}">
<ComboBox.ItemTemplate>
<DataTemplate>
<CheckBox IsChecked="{Binding IsChecked}" Content="{Binding Text}"
PreviewMouseDown="FilterComboBox_PreviewMouseDown"/>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
And then my event handler is:
private void FilterComboBox_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
var cb = sender as CheckBox;
if (cb != null)
{
cb.IsChecked = !cb.IsChecked;
e.Handled = true;
}
}

WPF Combobox: Different template in textbox and drop-downlist

This is my combo-box.
<ComboBox Height="45" HorizontalAlignment="Left" Margin="184,66,0,0" Name="ComboBox1" VerticalAlignment="Top" Width="216">
<ComboBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<Label Content="{Binding FullName}" Width="150" />
<Label Content="{Binding Title}" Width="100"/>
<Label Content="{Binding BranchName}" />
</StackPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
How can I change it so that only the FullName appears in the textbox portion of the combobox while all three columns still appear in the drop-down portion?

Unfortunately, the SelectionBoxItemTemplate is a readonly property, so we have to do a bit more work. By doing the ItemTemplate to be how you want the item to appear when selected, you can edit the ItemContainerStyle to provide a ControlTemplate that includes the other fields you want to display.
<ComboBox Height="45" HorizontalAlignment="Left" Margin="184,66,0,0" Name="ComboBox1" VerticalAlignment="Top" Width="216">
<ComboBox.ItemTemplate>
<DataTemplate>
<Label Content="{Binding FullName}" Width="150" />
</DataTemplate>
</ComboBox.ItemTemplate>
<ComboBox.ItemContainerStyle>
<Style TargetType="{x:Type ComboBoxItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBoxItem}">
<Border x:Name="Bd"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
Background="{TemplateBinding Background}">
<StackPanel Orientation="Horizontal">
<ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
VerticalAlignment="{TemplateBinding VerticalContentAlignment}" />
<Label Content="{Binding Title}" Width="100"/>
<Label Content="{Binding BranchName}" />
</StackPanel>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsHighlighted" Value="True">
<Setter TargetName="Bd" Property="Background" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}" />
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}" />
</Trigger>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ComboBox.ItemContainerStyle>
</ComboBox>
For the ComboBoxItem template, I just modified the default one, so it should be fully functional.

If the ComboBox's IsEditable property is set to True, you can set the "TextSearch.TextPath" property of the ComboBox to the property name you want to show. So in your case:
<ComboBox IsEditable="True" TextSearch.TextPath="FullName" .../>

Instead of using the read-only SelectionBoxItemTemplate property I created a new (attached, writable) property and used that one in my style. I also added a trigger to my style to not break all the comboboxes that are not using my new attached property...
Use it like this:
<ComboBox ItemsSource="{Binding ...}" SelectedItem="{Binding ..., Mode=TwoWay}">
<controls:ComboBoxSelectionBoxAltTemplateBehaviour.SelectionBoxAltTemplate>
<DataTemplate DataType="{x:Type ...}">
... Template for the selection box ...
</DataTemplate>
</controls:ComboBoxSelectionBoxAltTemplateBehaviour.SelectionBoxAltTemplate>
<ComboBox.ItemTemplate>
<DataTemplate DataType="{x:Type ...}">
... Template for the popup ...
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
You just have to add this class to your project:
public class ComboBoxSelectionBoxAltTemplateBehaviour
{
public static readonly DependencyProperty SelectionBoxAltTemplateProperty = DependencyProperty.RegisterAttached(
"SelectionBoxAltTemplate", typeof (DataTemplate), typeof (ComboBoxSelectionBoxAltTemplateBehaviour), new PropertyMetadata(default(DataTemplate)));
public static void SetSelectionBoxAltTemplate(DependencyObject element, DataTemplate value)
{
element.SetValue(SelectionBoxAltTemplateProperty, value);
}
public static DataTemplate GetSelectionBoxAltTemplate(DependencyObject element)
{
return (DataTemplate) element.GetValue(SelectionBoxAltTemplateProperty);
}
}
and change your ComboBox style to use the SelectionBoxAltTemplate attached property if set (or because I could not set a trigger to "not null", I set it back to the default SelectionBoxItemTemplate if the attached one is null):
The ContentPresenter inside the ControlTemplate of the ComboBox Style:
<ContentPresenter Content="{TemplateBinding SelectionBoxItem}" ContentTemplate="{TemplateBinding controls:ComboBoxSelectionBoxAltTemplateBehaviour.SelectionBoxAltTemplate}" />
And the Trigger to provide backwards compatibility to ComboBoxed without the attached Property:
<ControlTemplate.Triggers>
<Trigger Property="controls:ComboBoxSelectionBoxAltTemplateBehaviour.SelectionBoxAltTemplate" Value="{x:Null}">
<Setter Property="ContentTemplate" Value="{Binding SelectionBoxItemTemplate, RelativeSource={RelativeSource TemplatedParent}}" TargetName="ContentSite" />
</Trigger>
...
</ControlTemplate.Triggers>
Full Style:
<Style x:Key="{x:Type ComboBox}" TargetType="{x:Type ComboBox}">
<Setter Property="SnapsToDevicePixels" Value="true" />
<Setter Property="HorizontalContentAlignment" Value="Stretch" />
<Setter Property="VerticalContentAlignment" Value="Center" />
<Setter Property="FontSize" Value="12" />
<Setter Property="Background" Value="{StaticResource ComboBoxBackground}"/>
<Setter Property="BorderBrush" Value="{StaticResource ComboBoxBorder}"/>
<Setter Property="Margin" Value="6"/>
<Setter Property="Padding" Value="3,3,5,3"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ComboBox}">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="Auto"/>
</Grid.ColumnDefinitions>
<Border Name="Border" Grid.ColumnSpan="2" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}"/>
<ToggleButton Name="ToggleButton2" Focusable="False" IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press" Grid.ColumnSpan="2" Background="Transparent"/>
<!-- Allows clicking anywhere on the combobox, not only the visible button on the right -->
<ToggleButton Focusable="false" Grid.Column="1" x:Name="ToggleButton" IsChecked="{Binding Path=IsDropDownOpen, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" ClickMode="Press" Style="{StaticResource ComboBoxToggleButton}"/>
<ContentPresenter HorizontalAlignment="Left" Margin="{TemplateBinding Control.Padding}" x:Name="ContentSite" VerticalAlignment="Center" Content="{TemplateBinding SelectionBoxItem}" ContentTemplate="{TemplateBinding controls:ComboBoxSelectionBoxAltTemplateBehaviour.SelectionBoxAltTemplate}" ContentTemplateSelector="{TemplateBinding ItemTemplateSelector}" IsHitTestVisible="False" />
<TextBox Visibility="Hidden" HorizontalAlignment="Left" Margin="{TemplateBinding Control.Padding}" x:Name="PART_EditableTextBox" Style="{x:Null}" VerticalAlignment="Center" Focusable="True" Background="Transparent" />
<Popup IsOpen="{TemplateBinding IsDropDownOpen}" Placement="Bottom" x:Name="Popup" Focusable="False" AllowsTransparency="True" PopupAnimation="Slide">
<Grid MaxHeight="{TemplateBinding MaxDropDownHeight}" MinWidth="{TemplateBinding ActualWidth}" x:Name="DropDown" SnapsToDevicePixels="True">
<Border x:Name="DropDownBorder" Background="{StaticResource ComboBoxBackground}" BorderBrush="{StaticResource ComboBoxBorder}" BorderThickness="1" Padding="0,4">
<ScrollViewer SnapsToDevicePixels="True" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" CanContentScroll="True" Style="{x:Null}" >
<StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained"/>
</ScrollViewer>
</Border>
</Grid>
</Popup>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="controls:ComboBoxSelectionBoxAltTemplateBehaviour.SelectionBoxAltTemplate" Value="{x:Null}">
<Setter Property="ContentTemplate" Value="{Binding SelectionBoxItemTemplate, RelativeSource={RelativeSource TemplatedParent}}" TargetName="ContentSite" />
</Trigger>
<Trigger Property="HasItems" Value="false">
<Setter Property="MinHeight" Value="95" TargetName="DropDownBorder" />
</Trigger>
<Trigger Property="IsGrouping" Value="true">
<Setter Property="ScrollViewer.CanContentScroll" Value="false" />
</Trigger>
<Trigger Property="IsEditable" Value="true">
<Setter Property="IsTabStop" Value="false" />
<Setter Property="Visibility" Value="Visible" TargetName="PART_EditableTextBox" />
<Setter Property="Visibility" Value="Hidden" TargetName="ContentSite" />
</Trigger>
<Trigger Property="IsMouseOver" Value="true" SourceName="ToggleButton2">
<Setter Property="Background" Value="{StaticResource ComboBoxMouseOver}" />
</Trigger>
<Trigger Property="HasItems" Value="False">
<Setter Property="IsEnabled" Value="False"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
However this might not work with ItemTemplateSelctors, only with one single template - but you could easily add an attached property "SelectionBoxAltTemplateSelector" which provides the selector and passes that one to the style.

There is a pretty good answer to your question here if you don't want to change the ComboBoxes style: https://stackoverflow.com/a/2277488/1070906
It uses a Trigger in the DataTemplate which looks if there is a ComboBoxItem somewhere above in the visual tree, which is not the case in the selection box.

You could override the ComboBox and change the SelectionBoxItemTemplate directly.
public class SelectionComboBox : ComboBox
{
#region Properties
#region Dependency Properties
public DataTemplate AltSelectionBoxItemTemplate
{
get { return (DataTemplate)GetValue(AltSelectionBoxItemTemplateProperty); }
set { SetValue(AltSelectionBoxItemTemplateProperty, value); }
}
public static readonly DependencyProperty AltSelectionBoxItemTemplateProperty =
DependencyProperty.Register("AltSelectionBoxItemTemplate", typeof(DataTemplate), typeof(SelectionComboBox), new UIPropertyMetadata(null, (s, e) =>
{
// For new changes...
if ((s is SelectionComboBox) && ((SelectionComboBox)s).Presenter != null && (e.NewValue is DataTemplate))
((SelectionComboBox)s).Presenter.ContentTemplate = (DataTemplate)e.NewValue;
// Set the new value
((SelectionComboBox)s).AltSelectionBoxItemTemplate = (DataTemplate)e.NewValue;
}));
#endregion
#region Internals
#region Elements
ContentPresenter Presenter { get; set; }
#endregion
#endregion
#endregion
#region Constructors
#endregion
#region Methods
#region Overrides
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
Presenter = this.GetTemplateChild("contentPresenter") as ContentPresenter;
// Directly Set the selected item template
if (AltSelectionBoxItemTemplate != null) Presenter.ContentTemplate = AltSelectionBoxItemTemplate;
}
#endregion
#endregion
}
Once you define the control, you could style it.
<controls:SelectionComboBox ItemsSource="{Binding ...}" SelectedItem="{Binding ..., Mode=TwoWay}">
<controls:SelectionComboBox.AltSelectionBoxItemTemplate>
<DataTemplate>
<!-- My Template Goes Here... -->
</DataTemplate>
</controls:SelectionComboBox.AltSelectionBoxItemTemplate>
</controls:SelectionComboBox>