> that uses the native GUI technologies of each platform it supports.
WPF is native on Windows, Win32/WinForms is also native on Windows. I'm assuming it uses Win32, although a third party FFI to WPF would be very, very nice.
Windows also has DirectUI, very alike WPF which it uses internally (and also has some 3rd-party OSS implementations).
WinForms/Win32 is the first UI platform that Windows supported. It's getting less used because of the new UI platforms.
I don't really understand how do they define WPF, UWP, XAML and DirectUI now or how do they compare. XAML was the language used behind WPF but it seems they have changed the terms.
Just using WPF controls without having access to the features that WPF provides is kinda pointless, though. Also nearly (?) all other platform-native toolkits use simple immediate-mode rendering, while WPF heavily uses templates and retained-mode vector graphics, so abstracting away custom drawing code for controls might prove a bit hard, for example.
If you only have a button and a text field and want to make stuff happen when the button is clicked, then I doubt there is any difference in whether it uses Win32 or WPF.
WPF is native on Windows, Win32/WinForms is also native on Windows. I'm assuming it uses Win32, although a third party FFI to WPF would be very, very nice.