WinForms TextBox Caret does not blink

[dakusan]

I'm using .NET Core 3.1, but another user on StackOverflow reported the same problem in .NET 5. And one user reported “Mine blinks 5-6 times then stops blinking.”.

I have a System.Windows.Forms.TextBox that I added to the form through the designer in Visual Studio 2019 C# to a “Windows Forms App (.NET Core)” project. The caret just stays solid and does not blink. The Win32 APIs don't seem to help and I can't find anything on the System.Windows.Forms.TextBox or its parent classes that may help.

To reproduce doesn't require anything more than adding a TextBox onto a Form.

Further technical details

dotnet --info
.NET Core SDK (reflecting any global.json):
Version: 3.1.401
Commit: 5b6f5e5005

Runtime Environment:
OS Name: Windows
OS Version: 6.1.7601
OS Platform: Windows
RID: win7-x64
Base Path: C:\Program Files\dotnet\sdk\3.1.401\

Host (useful for support):
Version: 3.1.7
Commit: fcfdef8d6b

.NET Core SDKs installed:
2.1.701 [C:\Program Files\dotnet\sdk]
3.1.401 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.21 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.21 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.21 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.1.7 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

[dotnet-issue-labeler[bot]]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[RussKie]

This is a standard Windows behaviour. It is reproducible in .NET Framework as well:

caret.mp4