How do you set X11 window hints using gtk4-rs?

Question

I am trying to write a GTK4 application in rust that should be compliant with parts of the Extended Window Manager Hints spec, but for that I need to be able to get and set X11 hints. In particular, I want to set _NET_WM_WINDOW_TYPE.

If I were to create a window as follows, how would I get/set X11 window hints?

let app = Application::new(Some("id"), Default::default());
let window = ApplicationWindow::new(app);

Answer 1

After a few days of trial and error, I arrived to the following solution:

use gdk_x11::x11::xlib::{PropModeReplace, XChangeProperty, XInternAtom, XA_ATOM};

fn set_window_props(window: &gtk::Window, prop_name: &str, prop_values: &Vec<&str>) {
    let display = window.display();
    let surface = window.surface().unwrap();
    let prop_name_cstr = CString::new(prop_name).unwrap();
    let prop_values_cstr: Vec<CString> = prop_values
        .iter()
        .map(|val| CString::new(*val).unwrap())
        .collect();
    unsafe {
        let xid: xlib::Window = surface.unsafe_cast::<X11Surface>().xid();
        let xdisplay: *mut xlib::Display = display.unsafe_cast::<X11Display>().xdisplay();
        let prop_name_atom = XInternAtom(xdisplay, prop_name_cstr.as_ptr(), xlib::False);
        let mut prop_values_atom: Vec<u64> = prop_values_cstr
            .into_iter()
            .map(|cstr| XInternAtom(xdisplay, cstr.as_ptr(), xlib::False))
            .collect();
        let num_values = prop_values_atom.len();
        let prop_values_c = prop_values_atom.as_mut_ptr();
        XChangeProperty(
            xdisplay,
            xid,
            prop_name_atom,
            XA_ATOM,
            32,
            PropModeReplace,
            prop_values_c as *const u8,
            num_values as i32,
        );
    }
}

This will set the replace the values of type XA_ATOM of the X11 Window property prop_name with the atom values prop_values.

For setting properties of type utf8, it is much simpler and cleaner to use gdk4_x11::X11Surface::set_utf8_property.