Telerik控件使用Expression_DarkTheme后引发Combobx下拉问题

之前在Telerik的官方论坛中发现了有人提出该问题，但官方并未给出解决方案。

官方的回应应该是说Telerik版本问题，但实际上应该不是，我也换到了最新的版本依然会有问题。

没有办法，只能另外定一个全局样式临时性解决该问题。解决方案如下：

其实就是按样式重写一下RadComboBoxItem的样式即可，把Resource加入到App.xaml当中去。

<ResourceDictionary 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">
    
    <!--重写Combobox下拉菜单样式-->
    <SolidColorBrush x:Key="ItemBackground_Selected" Color="#FF878787" />
    <SolidColorBrush x:Key="ItemForeground_Selected" Color="#FF262626" />
    <ControlTemplate x:Key="RadComboBoxItemTemplate" TargetType="telerik:RadComboBoxItem">
        <Border x:Name="Background" BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="{TemplateBinding BorderBrush}" Background="{TemplateBinding Background}">
            <VisualStateManager.VisualStateGroups>
                <VisualStateGroup x:Name="CommonStates">
                    <VisualState x:Name="Normal" />
                    <VisualState x:Name="MouseOver">
                        <Storyboard>
                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Highlight" Storyboard.TargetProperty="(UIElement.Visibility)">
                                <DiscreteObjectKeyFrame KeyTime="0:0:0">
                                    <DiscreteObjectKeyFrame.Value>
                                        <Visibility>Visible</Visibility>
                                    </DiscreteObjectKeyFrame.Value>
                                </DiscreteObjectKeyFrame>
                            </ObjectAnimationUsingKeyFrames>
                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Content" Storyboard.TargetProperty="(ContentControl.Foreground)">
                                <DiscreteObjectKeyFrame KeyTime="0:0:0" Value="{StaticResource ItemForeground_Selected}" />
                            </ObjectAnimationUsingKeyFrames>
                        </Storyboard>
                    </VisualState>
                    <VisualState x:Name="Disabled" />
                </VisualStateGroup>
            </VisualStateManager.VisualStateGroups>
            <Grid>
                <Rectangle x:Name="Highlight" Fill="{StaticResource ItemBackground_Selected}" Visibility="Collapsed" />
                <ContentPresenter x:Name="Content" Margin="{TemplateBinding Padding}" 
                            HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" 
                            VerticalAlignment="{TemplateBinding VerticalContentAlignment}" />
            </Grid>
        </Border>
    </ControlTemplate>

    <Style x:Key="RadComboBoxItemStyle" TargetType="telerik:RadComboBoxItem">
        <Setter Property="Background" Value="Transparent" />
        <Setter Property="Template" Value="{StaticResource RadComboBoxItemTemplate}" />
        <Setter Property="HorizontalContentAlignment" Value="Stretch" />
        <Setter Property="VerticalContentAlignment" Value="Stretch" />
        <Setter Property="Padding" Value="3 6" />
        <Setter Property="FocusVisualStyle" Value="{x:Null}" />
    </Style>
    <Style TargetType="telerik:RadComboBoxItem" BasedOn="{StaticResource RadComboBoxItemStyle}" />
</ResourceDictionary>