https://www.alternetsoft.com/news/introducing-alternet-ui

Introducing AlterNET UI

A cross-platform .NET UI Framework for developing desktop user interfaces that work and look native under Windows, macOS and Linux.
12 December 2021

We would like to announce the very first beta of AlterNET UI - a cross-platform .NET UI Framework that allows the creation of desktop interfaces with .NET development tools that work and look native under Windows, macOS, and Linux.

AlterNET UI cross-platform framework

AlterNET UI provides a UI Framework and a set of standard controls such as Text Box, Label, CheckBox, Button, Image, TreeView, ListView, and many more.

AlterNET UI key elements

AlterNET UI is built on top of the .NET Framework and uses a XAML-like approach to define the user interface and layout, allowing .NET developers to immediately use their skills to create cross-platform or native macOS/Linux applications.

The design of the AlterNET UI is inspired by Windows Forms and Windows Presentation Foundation (WPF) frameworks from Microsoft, which makes .NET developers already familiar with the basic concepts of AlterNET UI programming.

The framework includes a layer that abstracts implementation on different platforms for graphical objects, such as fonts, brushes, images, control rendering and responding to the events, layout engine, and custom theme APIs.