More web refactor. Tighten suspend terminal code.

tests/test_input_event_manager_key_watcher_regressions.py

@@ -306,5 +306,25 @@ class InputEventManagerKeyWatcherTests(unittest.TestCase):
             [(modified, None), (unrelated, None)],
         )
 
+    def test_keybinding_grab_failure_rolls_back_partial_additions(self) -> None:
+        manager = input_event_manager.InputEventManager()
+        device = mock.Mock()
+        device.add_key_grab.side_effect = [101, RuntimeError("grab failed")]
+        manager._device = device
+        firstDefinition = types.SimpleNamespace(keycode=44, modifiers=0)
+        secondDefinition = types.SimpleNamespace(keycode=45, modifiers=0)
+        binding = mock.Mock()
+        binding.is_enabled.return_value = True
+        binding.is_bound.return_value = True
+        binding.has_grabs.return_value = False
+        binding.keycode = 44
+        binding.key_definitions.return_value = [firstDefinition, secondDefinition]
+
+        with self.assertRaisesRegex(RuntimeError, "grab failed"):
+            manager.add_grabs_for_keybinding(binding)
+
+        device.remove_key_grab.assert_called_once_with(101)
+        self.assertEqual(manager._grabbed_bindings, {})
+
 if __name__ == "__main__":
     unittest.main()