Events run from top to bottom. If there are two events which have been triggered in the same tick (imagine two identical events, for example), the one that is higher up will perform it's actions first. The exception is triggered events. Any event with a small green arrow to left of it's name is a triggered event. Right when the condition happens, the event is called. So you can have a start of layout event, which is a trigger, at the bottom of the event sheet, and it will still be the first event to run. However, if there is another start of layout trigger above it in the event sheet, then the top to bottom rule applies once again. Thirdly, you can use the function object to call events through actions.