See-through window on macOS: separate sidebar and main area opacity, with blur

[Garberchov]

On macOS, I would like T3 Code's window to be see-through, with the desktop blurred behind it, the way Finder and other macOS sidebars look. The existing Glass opacity setting only affects surfaces inside the app (the composer and dialogs), so the window itself stays solid.

What I have in mind:

• Sidebar opacity and main area opacity, set separately. Only the backgrounds fade; text stays solid.
• A blur switch (macOS vibrancy behind the window), so what shows through sits back instead of competing with the text.
• Off by default, so nothing changes for anyone who doesn't turn it on.

I prototyped it locally without changing the app bundle. Electron vibrancy on the main window, a transparent window background, and translucent backgrounds on data-slot="sidebar-inner", data-slot="sidebar-inset" and the full-size bg-background panels. It looks good in thread views. One thing to know: the behind-window blur added noticeable GPU load and made the UI stutter for me, so a built-in version would need to be careful about cost (for example, blur only while the window is focused, or no blur with plain transparency).