with picking.
When a condition matches an object, the actions will apply only to the objects that fulfilled the condition.
For example, if you have
+on collision door with car
- set value 'door_opening' to 1
+compare global('door_opening') to 1
there is no relationship between the sprite that triggered the event to the action. But if instead you do something like
+on collision door with car
only the door that collided with the car will be set to 0,0