[Winforms] Fixes Ctrl+C signal handling in WinForms platform

Author: r0x0r

webview/platforms/winforms.py

@@ -1,6 +1,7 @@
 import ctypes
 import logging
 import os
+import signal
 import sys
 import tempfile
 import threading
@@ -33,6 +34,20 @@
 kernel32 = ctypes.WinDLL('kernel32', use_last_error=True)
 logger = logging.getLogger('pywebview')
 cache_dir = None
+_sigint_received = False
+
+
+def _sigint_handler(signum, frame):
+    """
+    Handler for SIGINT signal (Ctrl+C).
+
+    Sets a flag that's checked by the timer in the GUI thread. This is necessary because
+    the signal handler runs in the main thread, but Application.Exit() must be called
+    from the GUI thread. The timer in create_window() checks this flag periodically and
+    exits the application when it's set.
+    """
+    global _sigint_received
+    _sigint_received = True
 
 
 def _is_new_version(current_version: str, new_version: str) -> bool:
@@ -748,11 +763,28 @@ def create():
         _main_window_created.set()
 
         if window.uid == 'master':
+
+            def timer_tick(sender, e):
+                # Check if SIGINT was received and exit from GUI thread
+                global _sigint_received
+                if _sigint_received:
+                    app.Exit()
+
+            # Create a timer to periodically allow the Python interpreter to run
+            # This enables the signal handler to be called even when the WinForms event loop is running
+            timer = WinForms.Timer()
+            timer.Interval = 500  # 500ms
+            timer.Tick += timer_tick
+            timer.Start()
+
             app.Run()
 
     app = WinForms.Application
 
     if window.uid == 'master':
+        # Set up Ctrl+C handler in main thread (before starting GUI thread)
+        signal.signal(signal.SIGINT, _sigint_handler)
+
         if is_chromium:
             init_storage()
 
@@ -765,7 +797,13 @@ def create():
         thread = Thread(ThreadStart(create))
         thread.SetApartmentState(ApartmentState.STA)
         thread.Start()
-        thread.Join()
+
+        # Don't use thread.Join() as it blocks the main thread indefinitely,
+        # preventing signal handlers from being processed. Instead, periodically
+        # check if the thread is still alive, which allows the Python interpreter
+        # to process pending signals (like SIGINT from Ctrl+C)
+        while thread.IsAlive:
+            thread.Join(500)
 
     else:
         _main_window_created.wait()