Use icon.visible to show or hide the tray icon on all systems

On Linux, pystray's icon.stop() currently doesn't work well with the
AppIndicator backend.

So, instead of destroying the icon when the user restores from tray
(only to later re-create it when the user minimizes to tray again), we
have the option to control the icon's visibility instead! Luckily, that
works on Windows too!

Note that for this change to work properly on Linux, we need to switch
to the master version of pystray, because we need this specific fix:

https://github.com/moses-palmer/pystray/commit/5943ed4e19be48224cf39b70444de8ffe22c23ce

After pystray releases a version newer than 0.19.4, we can switch back.

Co-authored-by: DevilXD <bartosz.peszek@gmail.com>

gui.py

@@ -1048,11 +1048,9 @@ class TrayIcon:
         self._button.grid(column=0, row=0, sticky="ne")
 
     def __del__(self) -> None:
+        self.stop()
         self.icon_image.close()
 
-    def is_tray(self) -> bool:
-        return self.icon is not None
-
     def get_title(self, drop: TimedDrop | None) -> str:
         if drop is None:
             return self.TITLE
@@ -1064,23 +1062,22 @@ class TrayIcon:
             f"{drop.progress:.1%} ({campaign.claimed_drops}/{campaign.total_drops})"
         )
 
-    def start(self):
-        if self.icon is None:
-            loop = asyncio.get_running_loop()
-            drop = self._manager.progress._drop
+    def _start(self):
+        loop = asyncio.get_running_loop()
+        drop = self._manager.progress._drop
 
-            # we need this because tray icon lives in a separate thread
-            def bridge(func):
-                return lambda: loop.call_soon_threadsafe(func)
+        # we need this because tray icon lives in a separate thread
+        def bridge(func):
+            return lambda: loop.call_soon_threadsafe(func)
 
-            menu = pystray.Menu(
-                pystray.MenuItem(_("gui", "tray", "show"), bridge(self.restore), default=True),
-                pystray.Menu.SEPARATOR,
-                pystray.MenuItem(_("gui", "tray", "quit"), bridge(self.quit)),
-            )
-            self.icon = pystray.Icon("twitch_miner", self.icon_image, self.get_title(drop), menu)
-            # self.icon.run_detached()
-            loop.run_in_executor(None, self.icon.run)
+        menu = pystray.Menu(
+            pystray.MenuItem(_("gui", "tray", "show"), bridge(self.restore), default=True),
+            pystray.Menu.SEPARATOR,
+            pystray.MenuItem(_("gui", "tray", "quit"), bridge(self.quit)),
+        )
+        self.icon = pystray.Icon("twitch_miner", self.icon_image, self.get_title(drop), menu)
+        # self.icon.run_detached()
+        loop.run_in_executor(None, self.icon.run)
 
     def stop(self):
         if self.icon is not None:
@@ -1091,13 +1088,16 @@ class TrayIcon:
         self._manager.close()
 
     def minimize(self):
-        if not self.is_tray():
-            self.start()
-            self._manager._root.withdraw()
+        if self.icon is None:
+            self._start()
+        else:
+            self.icon.visible = True
+        self._manager._root.withdraw()
 
     def restore(self):
-        if self.is_tray():
-            self.stop()
+        if self.icon is not None:
+            # self.stop()
+            self.icon.visible = False
         self._manager._root.deiconify()
 
     def notify(
@@ -1107,7 +1107,7 @@ class TrayIcon:
         if not self._manager._twitch.settings.tray_notifications:
             return None
         if self.icon is not None:
-            icon = self.icon
+            icon = self.icon  # nonlocal scope bind
 
             async def notifier():
                 icon.notify(message, title)