Media controls (MPRIS, Windows SMTC); stop old tracks when switching

Main.py

@@ -14,6 +14,7 @@ import sys
 import flet as ft
 
 from AudioMode import AudioMode
+from MediaControls import Remote
 from Core import (
     AppName, ApplyAppearance, AssetsDir, BuildTheme, BundledFontFamily, ChipButtonStyle, DataHome, EffectiveSettings,
     IsWindows, LoadConfig, Palette,
@@ -200,11 +201,20 @@ def Main(Page: ft.Page) -> None:
 
     Page.on_keyboard_event = OnKey
 
+    async def Quit() -> None:
+        """The window's close button and the media controls' Quit. Only
+        once: destroying the window sends another close event."""
+        if State.get("Quitting"):
+            return
+        State["Quitting"] = True
+        ModeViews["Music"].SaveSession()
+        Config.Save()  # the volume
+        await Controls.Stop()
+        await Page.window.destroy()
+
     async def OnWindowEvent(e: ft.WindowEvent) -> None:
         if e.type == ft.WindowEventType.CLOSE:
-            ModeViews["Music"].SaveSession()
-            Config.Save()  # the volume
-            await Page.window.destroy()
+            await Quit()
 
     Page.window.prevent_close = True
     Page.window.on_event = OnWindowEvent
@@ -232,6 +242,13 @@ def Main(Page: ft.Page) -> None:
         Page.run_task(ModeViews["Audio"].Open, Files)
     else:
         SwitchMode(Config.StartMode if Config.StartMode in ModeViews else "Music")
+
+    # The system's media controls follow whichever mode played last.
+    Controls = Remote(Page, Players, ModeViews, State["Mode"], SetVolume, Quit)
+    if Config.MediaControls:
+        TheApp.MediaChanged = Controls.MediaChanged
+        TheApp.MediaModesChanged = Controls.ModesChanged
+        Page.run_task(Controls.Start)
     Page.run_task(ModeViews["Music"].Started)
     Page.run_task(Ticker, [Mode.Bar for Mode in ModeViews.values()])