a simple example to get a graphical or game window and GUI going in F# with Veldrid and ImGUI

VeldridImGUI.fs

module ElmEye
open Veldrid
open Veldrid.StartupUtilities

let CreateApp windowWidth windowHeight name = 
    let windowCI = WindowCreateInfo(
                          X = 400,
                          Y =400, 
                          WindowWidth = windowWidth,
                          WindowHeight = windowHeight,
                          WindowTitle = name
                          )
    let window = VeldridStartup.CreateWindow(windowCI)
    window.add_Closed (fun () -> exit 0  |>ignore )
    window.Resizable <- true
    window.BorderVisible <-true
    window

open System.Diagnostics
open System.Numerics
open ImGuiNET

[<EntryPoint>]
let main argv =
    let window = CreateApp 640 480 "ElmEye"
    let gdo = GraphicsDeviceOptions()
    let gd = VeldridStartup.CreateGraphicsDevice(window)
    
    let gui = new ImGuiRenderer(gd, (gd.MainSwapchain.Framebuffer.OutputDescription),window.Width, window.Height)
    let sw = Stopwatch.StartNew()
    let mutable lastFrame = sw.ElapsedMilliseconds
    
    window.add_Resized ( fun ()-> gd.ResizeMainWindow(uint32 window.Width,uint32 window.Height)
                                  gui.WindowResized(window.Width, window.Height) 
                                  )
    
    while window.Exists do
        let cl = gd.ResourceFactory.CreateCommandList()
        let events = window.PumpEvents()
        
        gui.Update( float32(sw.ElapsedMilliseconds - lastFrame) ,events)
        

        //If the font is too small
        //ImGui.SetWindowFontScale (float32 1.8)
        
        //Use these commands to create an anchor-style panel
        ImGui.SetNextWindowSize(Vector2(float32 (window.Width/2), float32 window.Height))
        ImGui.SetNextWindowPos( Vector2(float32 0,float32 0), ImGuiCond.Always)
        ImGui.Begin("main", ImGuiWindowFlags.NoMove 
                        ||| ImGuiWindowFlags.NoCollapse 
                        ||| ImGuiWindowFlags.NoTitleBar 
                        ||| ImGuiWindowFlags.NoResize)|>ignore
        ImGui.Text "Hello Veldrid"
        ImGui.End()
        
        //the actual Veldrid drawing part
        cl.Begin()
        cl.SetFramebuffer(gd.MainSwapchain.Framebuffer)

        //A simple interaction to show you how to capture mouse events in GUI vs your game
        if ImGui.GetIO().WantCaptureMouse then
            cl.ClearColorTarget(uint32 0 , RgbaFloat.Black)
        else
            cl.ClearColorTarget(uint32 0 , RgbaFloat.CornflowerBlue)
        gui.Render (gd, cl)
        cl.End()

        gd.SubmitCommands cl
        gd.SwapBuffers()
    printfn "%A" argv
    0 // return an integer exit code