Refactor signal disconnection logic for improved safety and readability

main.py

@@ -2589,12 +2589,6 @@ class MainWindow(QtWidgets.QMainWindow):
             for widget in QtWidgets.QApplication.allWidgets():
                 if hasattr(widget, 'img_preview') and hasattr(widget.img_preview, 'clear'):
                     widget.img_preview.clear()
-                # Disconnect any remaining signal connections
-                if hasattr(widget, 'disconnect'):
-                    try:
-                        widget.disconnect()
-                    except:
-                        pass
         except:
             pass
         
@@ -4363,10 +4357,16 @@ class MainWindow(QtWidgets.QMainWindow):
         # Update global delay controls
         if self.current_scenario:
             # Temporarily disconnect signals to prevent triggering auto-save during loading
-            self.before_action_spinbox.valueChanged.disconnect()
-            self.after_action_spinbox.valueChanged.disconnect()
-            self.before_step_spinbox.valueChanged.disconnect()
-            self.after_step_spinbox.valueChanged.disconnect()
+            for sig in (
+                self.before_action_spinbox.valueChanged,
+                self.after_action_spinbox.valueChanged,
+                self.before_step_spinbox.valueChanged,
+                self.after_step_spinbox.valueChanged,
+            ):
+                try:
+                    sig.disconnect()
+                except Exception:
+                    pass
             
             # Load global delay settings
             global_delay = self.current_scenario.global_delay
@@ -4381,11 +4381,17 @@ class MainWindow(QtWidgets.QMainWindow):
             self.before_step_spinbox.valueChanged.connect(self._on_global_delay_changed)
             self.after_step_spinbox.valueChanged.connect(self._on_global_delay_changed)
         else:
-            # Reset to default values when no scenario is selected
-            self.before_action_spinbox.valueChanged.disconnect()
-            self.after_action_spinbox.valueChanged.disconnect()
-            self.before_step_spinbox.valueChanged.disconnect()
-            self.after_step_spinbox.valueChanged.disconnect()
+            # Reset to default values when no scenario is selected (safe disconnects)
+            for sig in (
+                self.before_action_spinbox.valueChanged,
+                self.after_action_spinbox.valueChanged,
+                self.before_step_spinbox.valueChanged,
+                self.after_step_spinbox.valueChanged,
+            ):
+                try:
+                    sig.disconnect()
+                except Exception:
+                    pass
             self.before_action_spinbox.setValue(0.0)
             self.after_action_spinbox.setValue(0.0)
             self.before_step_spinbox.setValue(0.0)