[.net-core] Is it possible to make desktop GUI application in .NET Core?

tl;dr - I'm not sure that it would be possible for the .NET Core developers to supply a cross-platform GUI framework.

I feel like expecting a cross-platform GUI framework to be bundled into the official tooling (especially an old version of the tooling - you mention that you're running Visual Studio 2015 update 3) for an early version of .NET Core is a little premature.

GUI frameworks are really quite heavy, and dependent on the hardware abstractions already present on the host machine. On Windows, there is generally a single window manager (WM) and desktop environment (DE) used by most users, but on the many different distributions of Linux which are supported, there are any number of possible WMs and DEs - granted most users will either be using X-Server or Wayland in combination with KDE, GNOME or Xfce. But no Linux installation ever is the same.

The fact that the open source community can't really settle on a "standard" setup for a VM and DE means that it would be pretty difficult for the .NET Core developers to create a GUI framework which would work across all platforms and combinations of DEs and WMs.

A lot of folks here have some great suggestions (from use ASP.NET Core to builds a Web application and use a browser to listing a bunch of cross-platform frameworks). If you take a look at some of the mentioned cross platform GUI frameworks listed, you'll see how heavy they are.

However, there is light at the end of the tunnel as Miguel de Icaza showed off Xamarin running naively on Linux and macOS at .NET Conf this year (2017, if you're reading this in the future), so it might be worth trying that when it's ready.

(But you'll need to upgrade from Visual Studio 2015 to Visual Studio 2017 to access the .NET Core 2.0 features.)