Add example for multiple simultaneous examples

examples/multiwindow.rs

@@ -0,0 +1,32 @@
+extern crate init = "gl-init-rs";
+extern crate libc;
+extern crate gl;
+
+fn main() {
+    let window1 = init::Window::new().unwrap();
+    let window2 = init::Window::new().unwrap();
+
+    spawn(proc() {
+        run(window1, (0.0, 1.0, 0.0, 1.0));
+    });
+
+    spawn(proc() {
+        run(window2, (0.0, 0.0, 1.0, 1.0));
+    });
+}
+
+fn run(window: init::Window, color: (f32, f32, f32, f32)) {
+    unsafe { window.make_current() };
+
+    gl::load_with(|symbol| window.get_proc_address(symbol) as *const libc::c_void);
+
+    gl::ClearColor(color.val0(), color.val1(), color.val2(), color.val3());
+
+    while !window.is_closed() {
+       window.wait_events().collect::<Vec<init::Event>>();
+
+        gl::Clear(gl::COLOR_BUFFER_BIT);
+
+        window.swap_buffers();
+    }
+}