Why is DialogResult a nullable bool in WPF?

Question

Can anyone think of a good explanation for the fact that result of a dialog is a nullable bool in WPF? This has always baffled me. In WinForms it was an enum type and that m

Answer 1

ShowDialog will always return true or false. DialogResult will only take the null state when the dialog is open. Transitioning from null to true or false will close the dialog and make the original call to ShowDialog return.