NumericUpDown: Shouldn't there be a single event for when the user made a change that should be acted upon?

Start by tracing NumericUpDown's ValueChanged handling, UpdateValueOnEnterKey behavior, and the spinner-related events described in the issue. Clarify the desired event semantics for Enter/Return, focus loss, and completed spinner changes; done means an agreed API that avoids per-keystroke actions while reporting the applied value.

When the user is editing a NumericUpDown, every keystroke raises a ValueChanged event. This is not ideal when it's linked to something that you don't want changed more frequently than necessary. In the past I have dealt with this by handling the KeyUp, LostFocus, and Spinned events like this:

private void TheIntegerUpDown_KeyUp(object sender, KeyEventArgs e)
{
	if (e.Key == Key.Enter || e.Key == Key.Return)
		if (TheIntegerUpDown.Value.HasValue)
			Update(TheIntegerUpDown.Value);
}

private void TheIntegerUpDown_LostFocus(object sender, RoutedEventArgs e)
{
	if (TheIntegerUpDown.Value.HasValue)
		Update(TheIntegerUpDown.Value);
}

private void TheIntegerUpDown_Spinned(object sender, Xceed.Wpf.Toolkit.SpinEventArgs e)
{
	if (TheIntegerUpDown.Value.HasValue && TheIntegerUpDown.Increment.HasValue)
	{
		if (e.Direction == Xceed.Wpf.Toolkit.SpinDirection.Increase)
			Update(TheIntegerUpDown.Value + TheIntegerUpDown.Increment);
		else if (e.Direction == Xceed.Wpf.Toolkit.SpinDirection.Decrease)
			Update(TheIntegerUpDown.Value - TheIntegerUpDown.Increment);
	}
}

This seem like a lot of code to handle something conceptually very simple. I see there is an UpdateValueOnEnterKey property which could simplify this a bit, but when that's set to true, using the up/down spinner buttons no longer raises the ValueChanged event. Furthermore, let's say you needed to look at multiple NumericUpDowns whenever a spinner button on one is used. You would need some mechanism to indicate one particular NumericUpDown's new value, while the others are unchanged.

I can envision a few ways of solving this, if an elegant solution does not exist already:

• An ActionableValueChanged event (couldn't come up with a better name) that's only raised when the user is typing and hits enter/return, the NumericUpDown loses focus, or a spinner button is pressed.
• A SpinCompleted event so one can easily get the NumericUpDown's Value after the change has been applied.