make sure the pop-up is closed when the main window is hidden

gotify_tray/gui/MainApplication.py

@@ -313,10 +313,13 @@ class MainApplication(QtWidgets.QApplication):
     def image_popup_callback(self, link: str, pos: QtCore.QPoint):
         if (filename := self.cache.lookup(link)) or (filename := self.downloader.get_filename(link)): # TODO: preload links
             self.image_popup = ImagePopup(filename, pos, link)
-            self.image_popup.show()
         else:
             # TODO
             logger.warning(f"Image {link} is not in the cache")
+    
+    def main_window_hidden_callback(self):
+        if image_popup := getattr(self, "image_popup", None):
+            image_popup.close()
 
     def refresh_callback(self):
         # Manual refresh -> also reset the image cache
@@ -372,6 +375,7 @@ class MainApplication(QtWidgets.QApplication):
         )
         self.main_window.delete_message.connect(self.delete_message_callback)
         self.main_window.image_popup.connect(self.image_popup_callback)
+        self.main_window.hidden.connect(self.main_window_hidden_callback)
 
         self.watchdog.closed.connect(lambda: self.listener_closed_callback(None, None))