Make progress bar cursor draggable

demo.py

@@ -55,6 +55,7 @@ class DemoController:
         self._track = {"song": "Harvest Moon", "artist": "Neil Young", "image": None}
         # Its play button only shows for a stream one of your accounts plays.
         self._account = next(iter(cfg.SPOTIFY_ACCOUNTS), None)
+        self._film_ms = 241000   # where the pretend Zidoo's film is, so a seek sticks
 
     # -- what the UI uses ---------------------------------------------
     def state(self):
@@ -74,7 +75,7 @@ class DemoController:
                 # Standing in for a Zidoo plugged into this input, so the
                 # AVR card's now-playing block has something to show here too.
                 "now_playing": {"song": "Big Buck Bunny", "artist": "2008", "image": None,
-                                "play_state": "play", "position_ms": 241000, "duration_ms": 596000}
+                                "play_state": "play", "position_ms": self._film_ms, "duration_ms": 596000}
                 if self.avr.current_input()["code"] == self.cfg.ZIDOO_INPUT_CODE else None,
             },
             "heos_ok": True,
@@ -119,6 +120,9 @@ class DemoController:
         self._joined = {k for k in self.cfg.ROOM_KEYS if k in joined}
         return self.joined_keys()
 
+    def zidoo_seek(self, position_ms):
+        self._film_ms = min(596000, int(position_ms))
+
     def joined_keys(self):
         return [k for k in self.cfg.ROOM_KEYS if k in self._joined]