Handle some keyboard shortcuts

src/lib/panzoom/util.ts

@@ -191,4 +191,12 @@ export function keepInBounds() {
   if (y > maxY) {
     transform.y = maxY;
   }
+}
+
+export function toggleFullScreen() {
+  if (!document.fullscreenElement) {
+    document.documentElement.requestFullscreen();
+  } else if (document.exitFullscreen) {
+    document.exitFullscreen();
+  }
 }