Menu separator not visible with light theme

[Klaus-Tockloth]

Checklist

• I have searched the issue tracker for open issues that relate to the same problem, before opening a new one.
• This issue only relates to a single bug. I will open new issues for any other problems.

Describe the bug

Menu separator not visible with light theme (windows, linux).

How to reproduce

Start application and activate menu.

Screenshots

OK:

NOK:

Example code

package main

import (
"fyne.io/fyne/v2"
"fyne.io/fyne/v2/app"
"fyne.io/fyne/v2/widget"
)

func main() {
application := app.New()
wMain := application.NewWindow("Menu Separator")
wMain.Resize(fyne.NewSize(400, 400))
hello := widget.NewLabel("Menu separators not shown under Windows.")
wMain.SetContent(hello)

generalHelp := fyne.NewMenuItem("General", func() {})
problemHelp := fyne.NewMenuItem("Problem", func() {})
versionHelp := fyne.NewMenuItem("Version", func() {})
helpMenu := fyne.NewMenu("Help", generalHelp, fyne.NewMenuItemSeparator(), problemHelp, fyne.NewMenuItemSeparator(), versionHelp)

mainMenu := fyne.NewMainMenu(helpMenu)
wMain.SetMainMenu(mainMenu)
wMain.ShowAndRun()

}

Fyne version

fyne version v2.3.3

Go compiler version

go version go1.20.3 darwin/arm64

Operating system and version

Windows 10 Pro (20H2)

Additional Information

No response

[andydotxyz]

Fixed on release branch for v2.3.5 :)