Port and re-write icon code.

src/lib/PaintCounter.tsx

@@ -0,0 +1,12 @@
+import { useState } from "preact/hooks";
+
+const counts: { [key: string]: number } = {};
+
+export default function PaintCounter() {
+    const [uniqueId] = useState('' + Math.random());
+    const count = counts[uniqueId] ?? 0;
+    counts[uniqueId] = count + 1;
+    return (
+        <span>Painted {count + 1} time(s).</span>
+    )
+}

src/lib/windowSize.ts

@@ -0,0 +1,24 @@
+import { useEffect, useState } from "preact/hooks";
+
+export function useWindowSize() {
+    const [windowSize, setWindowSize] = useState({
+        width: window.innerWidth,
+        height: window.innerHeight
+    });
+
+    useEffect(() => {
+        function handleResize() {
+            setWindowSize({
+                width: window.innerWidth,
+                height: window.innerHeight
+            });
+        }
+
+        window.addEventListener("resize", handleResize);
+        handleResize();
+
+        return () => window.removeEventListener("resize", handleResize);
+    }, []);
+
+    return windowSize;
+}