X11: calling Screen::get_monitors panics

[maan2003]

use druid::widget::SizedBox;
use druid::{AppLauncher, Screen, WindowDesc};

pub fn main() {
    Screen::get_monitors();
    let main_window = WindowDesc::new(SizedBox::empty());
    AppLauncher::with_window(main_window)
        .log_to_console()
        .launch(())
        .expect("Failed to launch application");
}

error:

'Main thread assertion failed 1 != 0', druid-shell/src/util.rs:39:9

useful parts of backtrace

   2: druid_shell::util::assert_main_thread
             at /src/druid/druid-shell/src/util.rs:39:9
   3: druid_shell::application::Application::try_global
             at /src/druid/druid-shell/src/application.rs:124:9
   4: druid_shell::backend::x11::screen::get_monitors
             at /src/druid/druid-shell/src/backend/x11/screen.rs:38:37
   5: druid_shell::screen::Screen::get_monitors
             at /src/druid/druid-shell/src/screen.rs:87:9