Why do Enter and Space keys behave differently for buttons?

Question

As far as I know, these are the only keys that react when a button has focus.

Pressing Enter instantly \'clicks\' the button, even if you keep it the key dow

Answer 1

You're seeing two different behaviors, which aren't associated except that they both deal with keyboard events on a winform.

Enter is special because it's the keypress to activate the acceptButton of a form. In fact, you missed another key that can affect buttons: Esc is the cancelButton, and will throw events as well.

As PhaDaPhunk explained, Space is a MouseClick for any component that accepts a MouseClick, but I haven't found a detailed explanation for it. I'd assume it's the default behavior of all controls. The Microsoft guide to accessibility seems to imply that is so in their section on keyboard-based navigation

Incidentally, this Microsoft support knowledge base entry seems to show that the spacebar implementation went from Button.Click to Button.MouseClick. Perhaps that's the reason for it's different behavior.