use fltk::{prelude::*, *}; fn main() { let app = app::App::default(); app::set_visible_focus(false); let mut win = window::Window::default().with_size(400, 300); win.set_color(enums::Color::White); let mut but = button::Button::default() .with_size(80, 40) .with_label("Expand!") .center_of_parent(); but.set_color(enums::Color::Cyan); but.set_frame(enums::FrameType::RFlatBox); win.end(); win.show(); but.set_callback(|b| { if b.y() == 0 { return; } let mut b = b.clone(); std::thread::spawn(move || loop { if b.y() == 0 { break; } b.resize(b.x() - 1, b.y() - 1, b.w() + 2, b.h()); app::sleep(0.005); b.parent().unwrap().redraw(); }); }); app.run().unwrap(); }