KeyDown repeats while key is held down

[billybednar]

Type of issue

Other (describe below)

Description

This article says that KeyDown occurs only once when a key is held down, however both KeyDown and KeyPress repeat in that case.

• The KeyDown event occurs once.
• The KeyPress event, which can occur multiple times when a user holds down the same key.

The related overview article also implies the same thing.

1. The user pushes the A key, the key is preprocessed, dispatched, and a KeyDown event occurs.
2. The user holds the A key, the key is preprocessed, dispatched, and a KeyPress event occurs. This event occurs multiple times as the user holds a key.

Handling User Input is also incorrect.

Raised only when a key is initially pressed.

Documentation of the actual behavior is a bit hard to come by, but KeyEventArgs has it right. In any event, it can easily be demonstrated:

var f = new System.Windows.Forms.Form();
f.KeyDown += (sender, e) => System.Diagnostics.Debug.WriteLine("KeyDown");
f.KeyPress += (sender, e) => System.Diagnostics.Debug.WriteLine("KeyPress");
f.KeyUp += (sender, e) => System.Diagnostics.Debug.WriteLine("KeyUp===========");
f.ShowDialog();

Output:

KeyDown
KeyPress
KeyDown
KeyPress
KeyDown
KeyPress
KeyUp===========

Page URL

https://learn.microsoft.com/en-us/dotnet/desktop/winforms/input-keyboard/events

Content source URL

https://github.com/dotnet/docs-desktop/blob/main/dotnet-desktop-guide/winforms/input-keyboard/events.md

Document Version Independent Id

6038a7fc-5a6f-06f9-ad06-dc7039c9909a

Platform Id

c9e78e28-c74b-fde5-a9df-e3e2b96001b3

Article author

@adegeo

Metadata

• ID: 6038a7fc-5a6f-06f9-ad06-dc7039c9909a
• PlatformId: c9e78e28-c74b-fde5-a9df-e3e2b96001b3
• Service: dotnet-desktop
• Sub-service: winforms

Related Issues

[adegeo]

Interesting! Did you test this across both .NET Framework and .NET 10 to see if it's some regression or just the way it's always been? What did you test with?

[billybednar]

I've tested it on 4.8, 9, and 10. My recollection is that it has always repeated, and I was surprised when I stumbled upon documentation saying otherwise. I did find a Stack Overflow post from nearly 17 years ago that says KeyDown repeats in contradiction to the documentation, so if it is a regression, it's certainly not a recent one.

The event doesn't necessarily have to match it, but WM_KEYDOWN is documented as repeating.