SDL2 + ImGui example in Beeflang

Program.cs

using System;
using ImGui;
using SDL2;

namespace Example
{
	public class Program
	{
		public static int Main(String[] args)
		{
			if (!ImGui.CHECKVERSION())
				Runtime.FatalError("ImGui version mismatch");

			SDL.Init(.Events);
			SDL.Window* window = SDL.CreateWindow("BFVM", .Centered, .Centered, 1080, 720, .OpenGL | .Maximized | .Resizable);
			SDL.SDL_GLContext glContext = SDL.GL_CreateContext(window);
			SDL.SDL_GL_MakeCurrent(window, glContext);
			SDL.GL_SetSwapInterval(1);

			ImGui.CreateContext();

			ImGui.IO* io = ImGui.GetIO();
			io.ConfigFlags |= .DockingEnable | .ViewportsEnable;
			io.ConfigViewportsNoDecoration = false;

			ImGuiImplOpenGL3.Init();
			ImGuiImplSDL2.InitForOpenGL(window, &glContext);

			GL.Init((proc) => SDL.SDL_GL_GetProcAddress(proc.Ptr));

			bool isRunning = true;
			while (isRunning)
			{
				while (SDL.PollEvent(var event) == 1)
				{
					ImGuiImplSDL2.ProcessEvent(&event);
					if (event.type == .Quit)
						isRunning = false;
					else if (event.type == .WindowEvent && event.window.windowEvent == .Close && event.window.windowID == SDL.GetWindowID(window))
						isRunning = false;
				}

				SDL.GetWindowSize(window, var width, var height);
				io.DisplaySize = .(width, height);

				ImGuiImplOpenGL3.NewFrame();
				ImGuiImplSDL2.NewFrame(window);
				ImGui.NewFrame();

				if (ImGui.BeginMainMenuBar())
				{
					if (ImGui.BeginMenu("File"))
						ImGui.EndMenu();
					ImGui.EndMainMenuBar();
				}

				var viewport = ImGui.GetMainViewport();
				ImGui.SetNextWindowPos(viewport.Pos);
				ImGui.SetNextWindowSize(viewport.Size);
				ImGui.SetNextWindowViewport(viewport.ID);

				ImGui.PushStyleVar(.WindowPadding, .(0, 0));
				ImGui.PushStyleVar(.WindowRounding, 0.0f);
				ImGui.PushStyleVar(.WindowBorderSize, 0.0f);
				ImGui.WindowFlags windowFlags = .NoResize | .NoMove | .NoBringToFrontOnFocus | .NoNavFocus;
				ImGui.Begin("MainDockspaceWindow", null, windowFlags);
				ImGui.PopStyleVar(3);

				ImGui.ID dockspaceId = ImGui.GetID("MainDockspace");
				ImGui.DockSpace(dockspaceId);

				if (ImGui.Begin("TEST"))
				{
					ImGui.End();
				}

				ImGui.End();
				ImGui.Render();
				GL.glViewport(0, 0, (.)io.DisplaySize.x, (.)io.DisplaySize.y);
				GL.glClearColor(0.2f, 0.2f, 0.2f, 1);
				GL.glClear(GL.GL_COLOR_BUFFER_BIT);
				ImGuiImplOpenGL3.RenderDrawData(ImGui.GetDrawData());

				if (io.ConfigFlags.HasFlag(.ViewportsEnable))
				{
					SDL.Window* backup_current_window = SDL.GL_GetCurrentWindow();
					SDL.SDL_GLContext backup_current_context = SDL.GL_GetCurrentContext();
		  #if BF_PLATFORM_WINDOWS
					ImGui.UpdatePlatformWindows();
					ImGui.RenderPlatformWindowsDefault();
		  #else
			#error Only windows is supported
		  #endif

					SDL.SDL_GL_MakeCurrent(backup_current_window, backup_current_context);
				}

				SDL.GL_SwapWindow(window);
			}

			ImGuiImplOpenGL3.Shutdown();
			ImGuiImplSDL2.Shutdown();
			ImGui.DestroyContext();

			SDL.GL_DeleteContext(glContext);
			SDL.DestroyWindow(window);
			SDL.Quit();

			return 0;
		}
	}
}