WPF input type/dialog box?

If you mean something like VB 6 Microsoft.VisualBasic.Interaction.InputBox there is nothing out of the box for both WinForms and WPF.

But of course many people coming from Delphi and VB6 are missing this you can find a lot of ready solutions in the Internet, for instance: http://www.codeproject.com/KB/edit/InputBox.aspx

To my knowledge there is no built-in dialogue for input (aside from MessageBox). You could create a window on the fly though if you do not want to subclass it. Just create a new window instance in code and set its Content to have some default Buttons (OK & Cancel) and a TextBox.