a quick test importing multiple GL versions with golang-ui/nuklear using 3.2 and creating a 3.3 context...

gonuk.go

package main

import (
	"fmt"
	"log"
	"runtime"

	_ "github.com/go-gl/gl/v3.2-core/gl"
	"github.com/go-gl/gl/v3.3-core/gl"
	"github.com/go-gl/glfw/v3.2/glfw"
	"github.com/golang-ui/nuklear/nk"
)

const (
	winWidth  = 400
	winHeight = 500

	maxVertexBuffer  = 512 * 1024
	maxElementBuffer = 128 * 1024
)

func init() {
	runtime.LockOSThread()
}

func main() {
	///////////////////////////////////////////////////////////////////////////
	// Setup OpenGL / GLFW
	if err := glfw.Init(); err != nil {
		fmt.Println(err)
		return
	}
	glfw.WindowHint(glfw.Samples, 4)
	glfw.WindowHint(glfw.ContextVersionMajor, 3)
	glfw.WindowHint(glfw.ContextVersionMinor, 3)
	glfw.WindowHint(glfw.OpenGLProfile, glfw.OpenGLCoreProfile)
	glfw.WindowHint(glfw.OpenGLForwardCompatible, glfw.True)
	win, err := glfw.CreateWindow(winWidth, winHeight, "Nuklear Demo", nil, nil)
	if err != nil {
		fmt.Println(err)
		return
	}
	win.SetSizeCallback(onWindowResize)
	win.MakeContextCurrent()
	glfw.SwapInterval(1)

	width, height := win.GetSize()
	log.Printf("glfw: created window %dx%d", width, height)

	if err := gl.Init(); err != nil {
		fmt.Printf("opengl: init failed: %v", err)
		return
	}
	gl.Viewport(0, 0, int32(width), int32(height))

	///////////////////////////////////////////////////////////////////////////
	// Setup Nuklear
	ctx := nk.NkPlatformInit(win, nk.PlatformInstallCallbacks)

	atlas := nk.NewFontAtlas()
	nk.NkFontStashBegin(&atlas)
	sansFont := nk.NkFontAtlasAddFromBytes(atlas, MustAsset("assets/FreeSans.ttf"), 16, nil)
	// sansFont := nk.NkFontAtlasAddDefault(atlas, 16, nil)
	nk.NkFontStashEnd()
	if sansFont != nil {
		nk.NkStyleSetFont(ctx, sansFont.Handle())
	}

	for !win.ShouldClose() {
		glfw.PollEvents()
		uiRender(win, ctx)
		win.SwapBuffers()
	}
}

func onWindowResize(w *glfw.Window, width int, height int) {
	//	renderer.ChangeResolution(int32(width), int32(height))
}

func uiRender(win *glfw.Window, ctx *nk.Context) {
	var bgColor nk.Color
	nk.NkPlatformNewFrame()

	// Layout
	bounds := nk.NkRect(50, 50, 230, 250)
	update := nk.NkBegin(ctx, "Demo", bounds,
		nk.WindowBorder|nk.WindowMovable|nk.WindowScalable|nk.WindowMinimizable|nk.WindowTitle)

	if update > 0 {
		nk.NkLayoutRowStatic(ctx, 30, 80, 1)
		{
			if nk.NkButtonLabel(ctx, "button") > 0 {
				log.Println("[INFO] button pressed!")
			}
		}
		nk.NkLayoutRowDynamic(ctx, 25, 1)
		{
			size := nk.NkVec2(nk.NkWidgetWidth(ctx), 400)
			if nk.NkComboBeginColor(ctx, bgColor, size) > 0 {
				nk.NkLayoutRowDynamic(ctx, 120, 1)
				bgColor = nk.NkColorPicker(ctx, bgColor, nk.ColorFormatRGBA)
				nk.NkLayoutRowDynamic(ctx, 25, 1)
				r, g, b, a := bgColor.RGBAi()
				r = nk.NkPropertyi(ctx, "#R:", 0, r, 255, 1, 1)
				g = nk.NkPropertyi(ctx, "#G:", 0, g, 255, 1, 1)
				b = nk.NkPropertyi(ctx, "#B:", 0, b, 255, 1, 1)
				a = nk.NkPropertyi(ctx, "#A:", 0, a, 255, 1, 1)
				bgColor.SetRGBAi(r, g, b, a)
				nk.NkComboEnd(ctx)
			}
		}
	}
	nk.NkEnd(ctx)

	bg := make([]float32, 4)
	nk.NkColorFv(bg, bgColor)
	width, height := win.GetSize()
	gl.Viewport(0, 0, int32(width), int32(height))
	gl.Clear(gl.COLOR_BUFFER_BIT)
	gl.ClearColor(bg[0], bg[1], bg[2], bg[3])
	nk.NkPlatformRender(nk.AntiAliasingOn, maxVertexBuffer, maxElementBuffer)
}