WPF 菜单实现一级二级按钮下拉格式<Expander Width="240" x:Name="myExpander"> <Expander.Header> <StackPanel Orientation="Horizontal" > <TextBlock Text="内容" /> <Image Width="20" Margin="15,0,0,0"> <Image.Style> <Style TargetType="Image"> <Style.Triggers> <DataTrigger Binding="{Binding IsExp