transparent_terminal_fail.vala

// valac test.vala --pkg vte-2.90 --pkg gtk+-3.0

public class App {
    Gtk.Window   _window;
    Vte.Terminal _terminal;
 
    public App(string[] args) {
        Gtk.init(ref args);
 
        _window = new Gtk.Window();
        _window.window_position = Gtk.WindowPosition.CENTER;
        _window.set_default_size(600, 500);
        _window.set_visual(Gdk.Screen.get_default().get_rgba_visual());
        _window.destroy.connect(Gtk.main_quit);
 
        _terminal = new Vte.Terminal();
        _terminal.set_background_image(null);
        _terminal.background_transparent = true;
        _terminal.set_opacity(0);
        _terminal.set_colors_rgba(
            make_transparent(parse_color("#FFFFFF")), // foreground
            make_transparent(parse_color("#333333")), // background
            {});                                      // palette
 
        _window.add(_terminal);
    }
 
    public Gdk.RGBA parse_color(string color_string) {
        Gdk.RGBA color = Gdk.RGBA();
        color.parse(color_string);
        return color;
    }
 
    public Gdk.RGBA make_transparent(Gdk.RGBA color) {
        color.alpha = 0;
        return color;
    }
 
    public void run() {
        _window.show_all();
        Gtk.main();
    }
}
 
void main(string[] args) {
    var app = new App(args);
    app.run();
}