"Depth Lock" option locks the layer of objects and can be used for rearranging the the sort of overlapped objects.

When the [Depth Lock Mode] option is off, the object you click the last will always come up the front, and when it is ON, you can select the object without changing the layers, so no matter what you click on, the layer of objects won't change.

For example, there are three classes in layers like this.











and you are going to click Class A.


- In case [Depth Lock Mode] is OFF :Class A will come up the front.












- In case [Depth Lock Mode] is ON :Class A is selected keeping the layer. (It's staying behind other classes.)










Cheers,
Satomi