Share System.Private.Windows.Core with WPF

[JeremyKuhne]

This core assembly has no dependencies. It provides helpful interop utilities and would allow sharing common functionality such as clipboard implementations.

As it is already available for WPF compilation, the initial plan is to add internals visible to for WPF assemblies and just consume it.

Vetting can be done by updating dotnet/wpf#7929 to use the shared code.

We'll likely want to move more CsWin32 imports and helper code down from System.Windows.Forms.Primitives.

[ThomasGoulet73]

Would it be better to make System.Private.Windows.Core public but without a ref assembly instead of using InternalsVisibleTo ?

It would then be "hidden" from projects referencing the WindowsDesktop pack but WPF would still be able to use it.

AFAIK InternalsVisibleTo is avoided when possible because it can cause issues with trimming. See dotnet/runtime#107848 for an example.

[AustinWise]

If WPF starts using System.Private.Windows.Core, the runtime pack needs to be updated to include it when publishing by updating it's profile here to be WindowsForms;WPF:

https:/dotnet/windowsdesktop/blob/main/src/windowsdesktop/src/sfx/Microsoft.WindowsDesktop.App.Runtime.sfxproj#L45

[RussKie]

If WPF starts using System.Private.Windows.Core, the runtime pack needs to be updated to include it when publishing by updating it's profile here to be WindowsForms;WPF:

dotnet/windowsdesktop@main/src/windowsdesktop/src/sfx/Microsoft.WindowsDesktop.App.Runtime.sfxproj#L45

Looks like that file (or the WindowsDesktop SDK) was refactored at some point, which lost the import and made the manual intervention necessary. This is wrong.
Windows Forms repo maintains and owns that list, and it is located here:

winforms/pkg/Microsoft.Private.Winforms/sdk/dotnet-windowsdesktop/System.Windows.Forms.FileClassification.props

Lines 1 to 24 in caf4fb9

	<!--
	This props file comes from dotnet/winforms. It gets ingested by dotnet/windowsdesktop and processed by
	pkg\windowsdesktop\sfx\Microsoft.WindowsDesktop.App.Ref.sfxproj.
	-->
	<Project>
	<ItemGroup Condition="'$(PackageTargetRuntime)' == ''">
	<FrameworkListFileClass Include="Microsoft.VisualBasic.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="Microsoft.VisualBasic.Forms.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Design.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Drawing.Common.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Drawing.Design.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Drawing.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Private.Windows.Core.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Windows.Forms.Analyzers.CodeFixes.CSharp.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Windows.Forms.Analyzers.CodeFixes.VisualBasic.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Windows.Forms.Analyzers.CSharp.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Windows.Forms.Analyzers.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Windows.Forms.Analyzers.VisualBasic.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Windows.Forms.Design.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Windows.Forms.Design.Editors.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Windows.Forms.dll" Profile="WindowsForms" />
	<FrameworkListFileClass Include="System.Windows.Forms.Primitives.dll" Profile="WindowsForms" />
	</ItemGroup>
	</Project>

The docs are here: https:/dotnet/winforms/tree/main/pkg/Microsoft.Private.Winforms#sdkdotnet-windowsdesktop-folder