[Feature Request]: Transparent background color support for WCO on Windows

[mitchchn]

Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Problem Description

Window Controls Overlay (WCO) allows for integrated titlebars can be styled to fit the look and feel of any app. But they are styled from the Electron main process, rather than in CSS, which means that there is no simple way to blend them into web content which is always changing.

Authors can set background and symbol colours which match a specific app configuration, but these colours have to be adjusted whenever the page styles change, e.g. due to theme changes, in-app navigation, or dimming caused by modals.

Proposed Solution

Allow color: undefined or color: "transparent" to be set in BrowserWindowOptions.titleBarOverlay.

Alternatives Considered

It is possible to style window controls at any time using BrowserWindow#setTitleBarOverlay (#33066). But web content in some apps is too dynamic for this solution to be practical -- any style change within the titlebar region would need a lifecycle event and IPC, just to simulate transparency at all times,

And because the overlay colour needs to be solid and opaque, there is no way to have the titlebar blend into all possible web content.

Additional Information

No response

[mitchchn]

It looks like it is possible to make the bar transparent using rgba, however this still has consequences:

#33764