This section explains the method show: in WAComponent.  show: is a variation of call:.  You may want to skip this section if you are new to Seaside.  You will find it helpful later on if you need to have more control on how components replace each other. 

The method show: passes the control from the receiving component to the component given as the first argument.  As with call: the receiver will be temporarily replaced by aComponent.  However, as opposed to call:, show: does not block the flow of control and immediately returns. 

If we replace the call: in the method editContact: with show: the application does not behave the same way as before anymore:

The reason is that show: does not block and the confirmation is displayed immediately, effectively replacing the ContactView.  Clicking on the Ok then reveals the ContactView.  Of course this is not the intended behavior.  We can fix this issue by assigning an answer handler to the view that displays the confirmation:

In fact, what we did above is continuation-passing style.  Like this we can emulate the blocking behavior of call: by using show: and a block that defines what happens afterwards.  Any code that uses call: can be transformed like this, however in case of loops that can become quite complicated (see Section 11.9.1).