calling UI updates from a Thread is an illegal operation

appEditors/appExcEditor.py

@@ -4313,9 +4313,13 @@ class AppExcEditor(QtCore.QObject):
             else:
                 self.edited_obj_name += "_edit"
 
+        def deactivate_signal_handler(_):
+            self.deactivate()
+
+        self.app.connect_custom_signal(deactivate_signal_handler, object)
         self.app.worker_task.emit({'fcn': self.new_edited_excellon,
                                    'params': [self.edited_obj_name, self.new_tools]})
-        self.deactivate()
+
 
         return self.edited_obj_name
 
@@ -4381,12 +4385,16 @@ class AppExcEditor(QtCore.QObject):
                                                                              filename=None,
                                                                              use_thread=False)
             except Exception as e:
+                self.app.custom_signal.emit(None) # calls deactivate_signal_handler() on UI Thread
+
                 # make sure that we do not carry the reference of the edited object further along
                 self.edited_obj = None
 
                 self.app.log.error("Error on Edited object creation: %s" % str(e))
                 return
 
+            self.app.custom_signal.emit(None)  # calls deactivate_signal_handler() on UI Thread
+
             # make sure that we do not carry the reference of the edited object further along
             self.edited_obj = None