Which is too bad, because there’s still no easy, drag and drop way to create desktop apps on other platforms that just work.

The drag and drop designer part of VS is not even what I think is cool about WPF. To me it's the architecture and the whole API. It's easy to make clean enterprise size applications with good separation of concerns (I've been a developer in the C#/WPF field for around 5 years). For other platforms - and Windows as well - the closest I know is Qt, including the drag and drop part btw. ;)

> the closest I know is Qt

Which you can use .NET Core with!

https://github.com/qmlnet/qmlnet

This always surprises me whenever I look into cross-platform GUI toolkits. The closest is Qt as you mentioned. What really gets me is GTK's continued popularity on Linux when Qt is so much easier to develop with.

Probably a hold over from Trolltech's original license for Qt. Also, GPL is a non-starter for a LOT of companies.

Probably a side effect from the popularity of Ubuntu which - since they dropped Unity - go still strong with GTK as they use Gnome now out of the box. And Ubuntu is like the de facto standard desktop distribution.

You can run UWP apps on all platforms using the Uno Platform.

https://platform.uno

How about Lazarus (https://www.lazarus-ide.org/)? Drag and drop to build the GUI, compile natively to Windows, Linux and MacOS.

What about java?

Jokes aside, license issues are the first that come to mind.

What license issues? OpenJDK is 100% free and open, and there are several OpenJDK providers that you can download it from.