Inane Ramblings of a .NET Developer - WPF - White Rectangle Instead of Window

I'm re-writing a Windows Form application using WPF as a way to
understand the basics. For a while I was banging my head against the
wall trying to do something really simple.
I was trying to launch another WPF window (form) as a modal dialiog
using ShowDialog as I would have done in wwindows Forms. Every time I
ran the application a large, blank white window appeared when the
ShowDialog call was made. This confused me until I realised I had
simply, accidentally deleted the designer-generated
InitializeComponent(); call from the Window's constructor.

These things always seem so obvious afterwards!