我使用的是 Visual Studio 2017 社區版/.NET Framework 4.6.1/WPF。順便提一句。我使用 MVVM。我的目標是在Combobox 中顯示所有可用的串行端口。我已經實現了這一點，但現在我想讓組合框在打開下拉菜單或連接新設備時自動更新。因此，我需要一些財產來制作Binding我的ViewModel.在 MSDN 上，我發現 Combobox.DroppedDown-Property 對我來說聽起來不錯，但我不能使用它，找不到 DroppedDown...（是System.Windows.Forms正確的參考嗎？）。你發現我的錯誤還是你有更好的解決方案？謝謝！<UserControl x:Class="HC_SR04_MPU6050.View.SerialView_MPU_6050"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"          xmlns:d="http://schemas.microsoft.com/expression/blend/2008"          xmlns:local="clr-namespace:HC_SR04_MPU6050.View"         mc:Ignorable="d"><Grid>    <Grid.ColumnDefinitions>        <ColumnDefinition Width="1*"/>        <ColumnDefinition Width="1*"/>        <ColumnDefinition Width="1*"/>        <ColumnDefinition Width="1*"/>        <ColumnDefinition Width="1*"/>    </Grid.ColumnDefinitions>    <Grid.RowDefinitions>        <RowDefinition Height="1*"/>        <RowDefinition Height="1*"/>    </Grid.RowDefinitions>    <Label Grid.Row="0" Content="MPU-6050" HorizontalAlignment="Center"/>    <Label Grid.Row="0" Grid.Column="3" Content="Y-ROT[°]" HorizontalAlignment="Center"/>    <Button Command="{Binding Connect_Clicked}" Grid.Row="1" Grid.Column="0" Content="Connect" Height="20" Width="60" VerticalAlignment="Center" HorizontalAlignment="Center" Margin="6" ToolTip="Opens/Connects the selected COM-PORT"/>    <Button Command="{Binding Measure_Clicked}" Grid.Row="1" Grid.Column="1" Content="MEASURE" Height="20" Width="60" VerticalAlignment="Center" HorizontalAlignment="Center" Margin="6" ToolTip="Starts the Measurement routine"/>    <Button Command="{Binding Stop_Clicked}" Grid.Row="1" Grid.Column="2" Content="STOP" Height="20" Width="60" VerticalAlignment="Center" HorizontalAlignment="Center" Margin="6" ToolTip="Stops the communication/ Closes/Disconnects the selected COM-PORT"/>