This is kinda difficult, but doable: you would have to look at GtkHeaderbar's window button implementation and basically copy that.

In GTK4 there's a widget for this specifically, alled GtkWindowControls, that you could overlay about your view though.

Also don't forget the controls can be on either side of the window, incl. both at once.

If this is easily doable using GTK4 I think that's a great path forward. For any DE supporting GTK4 it could allow this feature.

it's not DE that should support GTK4, it's Electron. A window is a window regardless of what toolkit it uses to draw it. However, GTK4 is not released yet. :p

Yep yep I know we're only on 3.38 :-), but it's nice to have a forward looking idea if possible!

3.38? Umm, 3.24... But ok.

Just forgot, another thing you will need in this case is to mask away window corners (the only reason headerbars have them is because they are not in the main window and so there's no content there, and bottom corners are impossible). I hope to get that into GTK4, but if you go with GTK3, there's a widget for that in libhandy (HdyWindow)