Terminate web-greeter gracefully

Set lightdm resettable property as true, so the greeter doesn't terminate
immediately after a successful start_session.

src/__main__.py

@@ -123,6 +123,7 @@ def parse(argv):
     from bridge import Greeter, Config, ThemeUtils
     from PyQt5.QtWidgets import QApplication
     from PyQt5.QtCore import Qt, QCoreApplication
+    from logger import logger
 
     QCoreApplication.setAttribute(Qt.AA_EnableHighDpiScaling)
     QApplication.setAttribute(Qt.AA_EnableHighDpiScaling)
@@ -141,3 +142,6 @@ def parse(argv):
     # browser.load()
     browser.show()
     browser.run()
+
+    logger.debug("App closed")
+    sys.exit(0)

src/bridge/Greeter.py

@@ -93,6 +93,7 @@ def __init__(self, *args, **kwargs):
         self._brightness_controller = BrightnessController()
 
         try:
+            LightDMGreeter.set_resettable(True)
             LightDMGreeter.connect_to_daemon_sync()
         except GError as err:
             logger.error(err)
@@ -367,13 +368,16 @@ def shutdown(self):
 
     @Bridge.method(str, result=bool)
     def start_session(self, session):
+        from PyQt5.QtCore import QCoreApplication
+
         if not session.strip():
             return False
         try:
             started: bool = LightDMGreeter.start_session_sync(session)
             if started or self.is_authenticated:
                 logger.debug("Session \"%s\" started", session)
                 screensaver.reset_screensaver()
+                QCoreApplication.quit() # Quit application after start_session
             return started
         except GError as err:
             logger.error(err)