CheckBoxs do not read their state to screen readers properly on change

[trypsynth]

.NET version

10.0.202

Did it work in .NET Framework?

Not tested/verified

Did it work in any of the earlier releases of .NET Core or .NET 5+?

No response

Issue description

This super simple test app:

using System.Windows.Forms;

ApplicationConfiguration.Initialize();
Form form = new() { Text = "Tiny App", Width = 200, Height = 100 };
CheckBox checkBox = new() { Text = "Check me!", Top = 20, Left = 20, AutoSize = true };
form.Controls.Add(checkBox);
Application.Run(form);

shows a problem with how Windows Forms handles its accessibility implementation for checkboxes.

1. With NVDA, both 64-bit 2026.1 and 32-bit 2025.x, pressing space to toggle the state of this checkbox is utterly silent, instead of saying "checked" or "unchecked".
2. With Narrator, it does read, but it rereads the entire label of the checkbox and then the state, which isn't normal. Went into an app using standard win32 controls and narrator announced "space, <state>" when I toggle checkboxes. In this app, it doesn't even say "space", just the label and the full state every time it's toggled.

Both of these are abnormal behaviors for screen readers, which points to it being something inside Winforms.

Steps to reproduce

1. Run my provided test app with a screen reader active.
2. Attempt to toggle the checkbox with the space bar.

[LeafShi1]

I haven't been able to reproduce the issue on my end. This is a .net10 project and my OS is Windows11 25H2

On my end, whenever I press the spacebar, Narrator reads "space" first, followed by the label and the control's state.

Narrator.mp4

With NVDA, when the control first receives focus, it reads the label, control type, and state; when the spacebar is pressed, it reads "space."
NVDA version 2024.4.2.35031

NVDA.mp4

[trypsynth]

@LeafShi1 I'm afraid I can't hear what you're trying to show me in these demos, I hear Microsoft david saying input capture and the window you're focusing and in the background very quietly I hear things like "space", "unchecked", but it's hard for me to make out. I'm on Windows 11 24H2, can provide a recording after work.

[LeafShi1]

@LeafShi1 I'm afraid I can't hear what you're trying to show me in these demos, I hear Microsoft david saying input capture and the window you're focusing and in the background very quietly I hear things like "space", "unchecked", but it's hard for me to make out. I'm on Windows 11 24H2, can provide a recording after work.

Sorry, I updated the video, please check it again. The fact that "space" isn't being announced might be due to a change in NVDA's implementation strategy, I noticed that after upgrading NVDA to version 2026.1.1, it no longer reads "space" either. I will investigate the issue regarding NVDA not announcing changes in control state further.