Input methods do not work
Hello, I have been going through the tutorial and the input examples do not work for me. Here is the first input example from the tutorial:

```lisp
(ql:quickload :sketch)
(use-package :sketch)

(defsketch input-test ((title "Hello, input")
                       (rectangles nil))
 (loop for (x y) in rectangles
       do (rect x y 50 50)))

(defmethod on-click ((window input-test) x y)
  (with-slots (rectangles) window
    (push (list x y) rectangles)))

(make-instance 'input-test)
```

The method does not get called. Even if I intentionally place an error like `(error "intentional")` at the start of the method body nothing happens on click.

I am running the following software:

- [Void Linux](https://voidlinux.org/)
- SBCL 2.4.3
- SDL 2.30.1
- SDL Image 2.8.2
- SDL TTF 2.20.2
- X11 with [BSPWM](https://github.com/baskerville/bspwm) as my window manager
- KDE Plasma 5.27.11 as my desktop environment
