How can I to detect if an Application been created with Winforms or WPF ?

Question

Without entering the code?

Answer 1

You could look at the DLLs the application loads (how to do something like that from c#). WPF classes are in completely different set of assemblies than WinForms classes.

This is not completely reliable though. Application can use both WinForms and WPF at the same time (and load both sets assemblies).

Answer 2

Well, you can use Snoop. If it appears in the list of applications you can "Snoop", that's a WPF app.