What is the purpose of the second-click selection mode in the interface builder?

Question

When I click the user interface element when designing the XIB, the user interface element is selected as follows:

If I click on the same element again, it will be selected as follows:

What is the purpose of this special selection mode?

Answer 1

Well, this is just a mechanism for moving the hierarchy of views (and locking focus on nested subviews). Although it seems that there is no difference between the two modes in your example (except, of course, the lack of resizing knobs in the "focused"), consider a more complex object, such as a table view on OSX (note also how the light blue color indicates an editable view, while the focus ring indicates its supervisor frame - also note that this sweep is based on the location of the mouse pointer.In this example, to go all the way to the cell, we have to click inside border innermost element to which we aspire to):

1st Click - select an external item / container (ScrollView)

2nd Click - Select TableView

Third click . Selects a TableColumn.

4th click - TableCell selection