Got it working, but it's not better than before...

wobuzz/player/player.py

@@ -1,5 +1,6 @@
 #!/usr/bin/python3
 
+import time
 import threading
 import pygame.mixer
 import pygame.event
@@ -174,6 +175,15 @@ class Player:
     def start_playlist(self, playlist):
         self.stop()
 
+        if not playlist.loaded:
+            playlist.load()
+
+        while not playlist.has_tracks() and not playlist.loaded:  # wait until first track is loaded
+            time.sleep(0.1)
+
+        if not playlist.has_tracks():
+            return
+
         self.current_sound, self.current_sound_duration = playlist.set_track(0)  # first track
         self.current_playlist = playlist
 

wobuzz/player/playlist.py

@@ -1,6 +1,7 @@
 #!/usr/bin/python3
 
 import os
+import threading
 from PyQt6.QtCore import Qt
 from .track import Track
 
@@ -18,7 +19,8 @@ class Playlist:
         self.tracks: list[Track] = []
         self.current_track_index = 0
         self.current_track: Track | None = None
-        self.view = None
+        self.views = {}  # dict of id(LibraryDock): PlaylistView
+        self.loaded = False
 
         self.path = os.path.expanduser(
             f"{app.settings.library_path}/playlists/{self.title.replace(" ", "_")}.wbz.m3u"
@@ -41,9 +43,13 @@ class Playlist:
 
             i += 1
 
-        # set current track to the first track if there is no currently playing track
-        if self.current_track is None and self.has_tracks():
-            self.current_track = self.tracks[0]
+        self.save()
+
+        self.tracks = []
+
+    def load(self):
+        loading_thread = threading.Thread(target=self.load_from_m3u, args=(self.path,))
+        loading_thread.start()
 
     def load_from_m3u(self, path):
         file = open(path, "r")
@@ -64,14 +70,18 @@ class Playlist:
 
                 continue
 
-            self.tracks.append(Track(self.app, line, cache=i==0))  # first track is cached
+            self.append_track(Track(self.app, line, cache=i==0))  # first track is cached
 
             i += 1
 
+        print("kolupp")
+
         # set current track to the first track if there is no currently playing track
         if self.current_track is None and self.has_tracks():
             self.current_track = self.tracks[0]
 
+        self.loaded = True
+
     def load_from_wbz(self, path):
         pass
 
@@ -149,10 +159,14 @@ class Playlist:
         self.app.library.playlists.remove(self)
 
     def append_track(self, track):
+        for dock_id in self.views:
+            view = self.views[dock_id]
+            view.append_track(track)
+
         self.tracks.append(track)
 
-        if self.view:
-            self.view.append_track(track)
+        print(track.tags.title)
+
 
     def h_last_track(self):
         # get last track in history (only gets used in player.history)