diff --git a/examples/boing.c b/examples/boing.c
index c6f225fbf..d517860d3 100644
--- a/examples/boing.c
+++ b/examples/boing.c
@@ -255,6 +255,18 @@ void key_callback( GLFWwindow* window, int key, int scancode, int action, int mo
 {
     if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
         glfwSetWindowShouldClose(window, GL_TRUE);
+
+    if (key == GLFW_KEY_ENTER && mods == GLFW_MOD_ALT && action == GLFW_PRESS)
+    {
+        if (glfwGetWindowMonitor(window))
+            glfwSetWindowMonitor(window, NULL, 640, 480);
+        else
+        {
+            GLFWmonitor* monitor = glfwGetPrimaryMonitor();
+            const GLFWvidmode* mode = glfwGetVideoMode(monitor);
+            glfwSetWindowMonitor(window, monitor, mode->width, mode->height);
+        }
+    }
 }
 
 static void set_ball_pos ( GLfloat x, GLfloat y )