func Menu(sTitle string) {
	if sMenu == "" {
		sMenu = "[\"menu\",["
	} else {
		if sMenu[len(sMenu)-1] != '[' {
			sMenu += ","
		}
		sMenu += "[\"" + sTitle + "\",["
		iStackLen++
	}
}
Menu starts a window's menu or submenu definition, sTitle is a menu title.
package external
import (
	"strconv"
	"encoding/json"
)
var sMenu = ""
var iStackLen = 0