Keep Win32 IME character events

src/textual/drivers/win32.py

@@ -78,6 +78,15 @@ class KEY_EVENT_RECORD(Structure):
     ]
 
 
+def _is_bare_modifier_key_event(key_event: KEY_EVENT_RECORD) -> bool:
+    """Check if a key event only represents modifier-key state."""
+    return (
+        bool(key_event.dwControlKeyState)
+        and key_event.wVirtualKeyCode == 0
+        and key_event.uChar.UnicodeChar in ("", "\x00")
+    )
+
+
 class MOUSE_EVENT_RECORD(Structure):
     """https://docs.microsoft.com/en-us/windows/console/mouse-event-record-str"""
 
@@ -270,10 +279,7 @@ def run(self) -> None:
                         key_event = input_record.Event.KeyEvent
                         key = key_event.uChar.UnicodeChar
                         if key_event.bKeyDown:
-                            if (
-                                key_event.dwControlKeyState
-                                and key_event.wVirtualKeyCode == 0
-                            ):
+                            if _is_bare_modifier_key_event(key_event):
                                 continue
                             append_key(key)
                     elif event_type == WINDOW_BUFFER_SIZE_EVENT:

tests/test_driver.py

@@ -1,5 +1,6 @@
 from textual import on
 from textual.app import App
+from textual.drivers.win32 import KEY_EVENT_RECORD, _is_bare_modifier_key_event
 from textual.events import Click, MouseDown, MouseUp
 from textual.widgets import Button
 
@@ -27,6 +28,15 @@ def handle(self, event):
         assert isinstance(app.messages[2], Click)
 
 
+def test_win32_ime_vk0_shift_character_is_not_bare_modifier():
+    key_event = KEY_EVENT_RECORD()
+    key_event.dwControlKeyState = 0x0010
+    key_event.wVirtualKeyCode = 0
+    key_event.uChar.UnicodeChar = "\uff1f"
+
+    assert not _is_bare_modifier_key_event(key_event)
+
+
 async def test_driver_mouse_down_up_click_widget():
     """Mouse down and up should issue a click when they're on a widget."""