讓VS2019支持.NET Core WinForms和WPF設計器的臨時辦法（比微軟給出的辦法更方便）

參考以下代碼片段，給項目添加NET Framework目標框架，切換到NET472運行時重新生成項目，然后打開設計器界面。
如果遇到設計器報錯，嘗試以NET472運行時為目標重新生成項目，並重新打開VS。

netcore3-winform-designer
netcore3-wpf-designer

Design in .NET Framework target, publish in .NET Core 3.

WinForm

<Project Sdk="Microsoft.NET.Sdk.WindowsDesktop">

  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFrameworks>net472;netcoreapp3.0</TargetFrameworks>
    <UseWindowsForms>true</UseWindowsForms>
    <LangVersion>7.3</LangVersion>
  </PropertyGroup>
  <ItemGroup Condition=" '$(TargetFramework)' == 'net472' ">
    <Reference Include="System" />
    <Reference Include="System.Core" />
    <Reference Include="System.Xml.Linq" />
    <Reference Include="System.Data.DataSetExtensions" />
    <Reference Include="Microsoft.CSharp" />
    <Reference Include="System.Data" />
    <Reference Include="System.Deployment" />
    <Reference Include="System.Drawing" />
    <Reference Include="System.Net.Http" />
    <Reference Include="System.Windows.Forms" />
    <Reference Include="System.Xml" />
  </ItemGroup>
  <ItemGroup Condition=" '$(TargetFramework)' == 'net472' ">
    <!-- add From files to here to enable designer -->
    <Compile Update="Form1.cs">
      <SubType>Form</SubType>
    </Compile>
  </ItemGroup>
</Project>

WPF

<Project Sdk="Microsoft.NET.Sdk.WindowsDesktop">

  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFrameworks>net472;netcoreapp3.0</TargetFrameworks>
    <UseWPF>true</UseWPF>
  </PropertyGroup>
  <ItemGroup Condition=" '$(TargetFramework)' == 'net472' ">
    <Reference Include="System" />
    <Reference Include="System.Data" />
    <Reference Include="System.Xml" />
    <Reference Include="Microsoft.CSharp" />
    <Reference Include="System.Core" />
    <Reference Include="System.Xml.Linq" />
    <Reference Include="System.Data.DataSetExtensions" />
    <Reference Include="System.Net.Http" />
    <Reference Include="System.Xaml">
      <RequiredTargetFramework>4.0</RequiredTargetFramework>
    </Reference>
    <Reference Include="WindowsBase" />
    <Reference Include="PresentationCore" />
    <Reference Include="PresentationFramework" />
  </ItemGroup>
  <ItemGroup Condition=" '$(TargetFramework)' == 'net472' ">
    <!-- add files to here to enable designer -->
    <Compile Update="App.xaml.cs">
      <DependentUpon>App.xaml</DependentUpon>
      <SubType>Code</SubType>
    </Compile>
    <Compile Update="MainWindow.xaml.cs">
      <DependentUpon>MainWindow.xaml</DependentUpon>
      <SubType>Code</SubType>
    </Compile>
  </ItemGroup>
</Project>

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