Control with the same behavior as "Type a question for help" or "Find contact"

[Komarnitsky]

Hello!

I create a AddIn for Outlook: add new CommandBar and
CommandBarComboBox. Set up a handler for Change event.

So now, when a enter something in my control and press "Tab" key -
Change event not occur.
Let's look for the original help control "Type a question for help" in
the upper right corner (or look at "Find contact" control). When I
enter some text there and press Tab key - text is dissapear. Some
event occur and outlook process it.

How does "microsoft" do this? Which event I must to process to do the
same behavior?
Or this is a "hard code" from Redmond guys?

I don't need the grey text like in original control - i just want to
process users input in the same way.