use fltk_sys::*; use std::os::raw::*; unsafe extern "C" fn cb(_wid: *mut button::Fl_Widget, data: *mut c_void) { let frame = data as *mut frame::Fl_Box; frame::Fl_Box_set_label(frame, "Hello World\0".as_ptr() as *const _); } fn main() { unsafe { fl::Fl_init_all(); image::Fl_register_images(); fl::Fl_lock(); let win = window::Fl_Window_new(100, 100, 400, 300, "Window\0".as_ptr() as *const _); let frame = frame::Fl_Box_new(0, 0, 400, 200, std::ptr::null()); let but = button::Fl_Button_new(160, 220, 80, 40, "Click\0".as_ptr() as *const _); window::Fl_Window_end(win); window::Fl_Window_show(win); button::Fl_Button_set_callback(but, Some(cb), frame as *mut _); fl::Fl_run(); } }