Fix MIST gallery scene controls, video positioning and audio overlap

frontend/tests/engine-behavior.test.mjs

@@ -8,6 +8,18 @@ const runtime = () => ({ game: { resolution: [640, 480], entry: "start", ui: {},
   transforms: {}, atl: {}, transitions: {}, screens: {}, styles: {}, audio: {} },
   modules: [{ labels: [{ name: "start", body: [{ op: "return" }] }], anchors: {} }] });
 
+test("enabling Skip interrupts an already running timed pause", async () => {
+  const { engine } = makeEngine(runtime());
+  try {
+    const pause = engine.pause(120);
+    assert.equal(typeof engine.onAdvance, 'function');
+    engine.setSkip(true);
+    await Promise.race([pause, new Promise((_, reject) => setTimeout(() => reject(new Error('Skip left the pause running')), 100))]);
+    assert.equal(engine.onAdvance, null);
+    assert.equal(engine.skipTick, null);
+  } finally { engine.destroy(); }
+});
+
 test("runtime image declarations produce scaled thumbnails and survive saving", () => {
   const { engine } = makeEngine(runtime());
   try {