What OS are you using (uname -a, or Windows version)?

Both Linux and Windows.

Linux:
Linux shougo-GE 5.4.0-74-generic #83-Ubuntu SMP Sat May 8 02:35:39 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Windows:
Windows 10 Enterprise 21H1

IE version: 11.789.19041.0
Edge: 91.0864.54

What programming language are you using (C/C++/Go/Rust)?

go version go1.16.5 linux/amd64

go version go1.16 windows/amd64

What did you expect to see and what you saw instead?

Expected: Destroy() should close webview window.

I have tested below sample script.
Destroy() is called after 5 seconds sleep, but the webview window does not be closed.
The window is only closed when the script is exited.

package main

import (
	"fmt"
	"time"

	"github.com/webview/webview"
)

func main() {
	runBrowser()

	fmt.Println("destroyed!")
	time.Sleep(5 * time.Second)
	fmt.Println("exit!")
}

func runBrowser() {
	debug := true
	w := webview.New(debug)
	defer w.Destroy()
	w.SetTitle("Minimal webview example")
	w.SetSize(800, 600, webview.HintNone)
	w.Navigate("http://www.google.co.jp/")

	go func() {
		fmt.Println("Closing in 5 seconds")
		time.Sleep(5 * time.Second)

		w.Dispatch(func() {
			w.Terminate()
		})
	}()

	w.Run()
}

I have read the code and it should close the window when Destroy() is called.

And in macOS the webview window close seems implemented.

Note: The destructor is called when Destroy() is called.

The behavior is changed when the code is merged?
843c3aa#diff-0332cdfa0ecdb4d0b79f675f5079e61cdc3e7f6f3c658a73c64973a1b35c2442

Related issue: #514
I think the above issue works because it is under macOS environment.