SplashScreen form not shown unless Startup Form set to Sub Main

[paul1956]

• .NET Core Version:
  Microsoft.WindowsDesktop.App 5.0.0

• Have you experienced this same bug with .NET Framework?:
  No

Problem description:

In Framework SplashScreen is shown if one is defined in project file and Project Startup object is set to Form1. In Core the splash screen is only shown if Startup object is set to Sub Main

Expected behavior:
SplashScreen is shown if Startup object is set to Form1

Minimal repro:
https://github.com/paul1956/WinForms5VBSample

[KlausLoeffelmann]

Paul, please note: When ever Sub Main is not the start object, you are bypassing the App Framework.
To set a different Form, currently we need to edit the Application.myapp file manually.
We're tracking the issue in Project System here:

dotnet/project-system#6787

[paul1956]

@KlausLoeffelmann What is missing is what the needed edits are in detail. Too much internal knowledge is assumed.

[paul1956]

There is a desire to make VB WinForm Apps . Net tools so they can simply be installed with DotNet Install, C# WinForm apps are supported but this issue seems to make it harder/impossible to do for VB.

https://docs.microsoft.com/en-us/dotnet/core/tools/global-tools-how-to-create