How to proceed with learning to code Windows desktop applications?

[DanielG]

There are far too many options for Windows GUI programming, so we 
probably need a bit more information about any constraints that 
are important to you.

For example:

- do you specifically want something that works well with D? or 
are you open to other languages?

- are you just wanting to learn desktop programming in general? 
(Like the concepts involved) Or do you have a specific thing you 
want to create?

I would personally suggest Delphi to somebody who wants to write 
Windows desktop apps and learn about event-driven development, 
howeverrr the language (Object Pascal) is insufferably archaic 
compared to something like D. But it is definitely the cleanest, 
least-overwhelming method of writing native Win32 applications 
for somebody with no prior experience.

Then there's all the modern Microsoft stuff (WPF/XAML/WinRT/etc), 
but you pretty much have to use either .NET or C++ for that.