How to instance an mx-component

Question

Hi!
I have the following problem.
1. I got a mx:ViewStack (main) with two components: an mx:HBox and a custom made (app:NewMailBox).
2. In the main application I want to open the app:NewMailBox and initate it with a mail object
Probelm
The components in app:NewMailBox is null the first time I call method newMail.setMail() (please see code below). The next time i works.
Conslusion
It seems like the mx components must be shown to be created.
Question
How do I create the instances of a mx components in a viewstack without showing it first. Please see code below for some clarification ;-)
<mx:VBox>
    <mx:ViewStack id="mainStack">
          <mx:HBox>
              <mx:DataGrid id="mailGrid" dataProvider="{mailList}"
                         click="mainStack.selectedIndex = 1; newMail.setMail(mailGrid.selectedItem);">
                         //The newMail mx components are null the first time setMail() method is called and the newMailBox component is shown
                         //The second time this meethod is called all mx child components to newMailBox is created and it works perfectly
                  <mx:columns>
                          <mx:DataGridColumn dataField="@subject" headerText="Title"/>
                  </mx:columns>
              </mx:DataGrid>
          </mx:HBox>
          <app:NewMailBox id="newMail"/>
    <mx:ViewStack>
</mx:VBox>
Best regards,
Mattias

Answer 1

I've heard the Adobe team say creationPolicy="all" is to be avoided if possible.
You need to initialize all objects that you will reference before they are shown to some default valule, even if that value is meaningless, just so it is not null.