RFR: 8313424: JavaFX controls in the title bar [v21]

[Thiago Milczarek Sayao]

On Tue, 5 Nov 2024 01:40:34 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

> > I'm not sure if it's feasible, but having a `GtkOverlay` seems to work on a basic app paintable C app:
> > Gtk4 even has [WindowControls](https://docs.gtk.org/gtk4/class.WindowControls.html).
> > I started to play with the CSS to make it transparent, but it does not seem much straightforward, but possible.
> > Running the program with `GTK_DEBUG=interactive` makes it easier.
> 
> The main problem with this approach is that it presupposes that the drawing is only done in GTK callbacks. But that's not how JavaFX interacts with GTK, so I think it will probably not work. I haven't found a way to simultaneously use the current JavaFX rendering approach and mix in GTK widgets on the same surface.

Yeah, didn't work. In theory it should work with Wayland and a subsurface, like [libdecor](https://gitlab.freedesktop.org/libdecor/libdecor) does. X11 has the concept of multiple stacked Windows, in theory it's possible, I just don't know how to sync it.

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PR Comment: https://git.openjdk.org/jfx/pull/1605#issuecomment-2457873484