Visual bell only flashes cells with no background

[crides]

What Operating System(s) are you seeing this problem on?

macOS

Which Wayland compositor or X11 Window manager(s) are you using?

No response

WezTerm version

20231003-071306-0700a6b1

Did you try the latest nightly build to see if the issue is better (or worse!) than your current version?

Yes, and I updated the version box above to show the version of the nightly that I tried

Describe the bug

When the window contains cells with background color, the visual bell flash won't flash those areas. This is obvious with tmux splits, where one of the panes is e.g. vim with a background color. Visual bell will then flash everywhere but the editor pane(s).

To Reproduce

1. enable visual_bell
2. start tmux
3. make a split
4. start vim / use bat in one of the panes
5. smash escape/backspace/echo -e "\a" in the other pane

Configuration

return {
    visual_bell = {
        fade_out_function = 'EaseOut',
        fade_out_duration_ms = 150,
    },
}

Expected Behavior

No response

Logs

No response

Anything else?

No response

[wez]

It's not a bug; the visual bell operates on the window background. If you have other cell attributes set that obscure it, you won't see the window background.