Asynchronous Operations and Message Boxes in the TUI (Windows CE 5.0)
The most important function of an IP phone is the ability to make and receive calls. Because a user might pick up the handset to make a call or receive a phone call at any time, the TUI application is designed to never block and be continually responsive.
To make this a reality, the TUI cannot show dialogs modally. Instead, all dialogs are nonmodal. This enables the TUI to always display the user interface for things like outgoing or incoming calls regardless of the current state of the application.
(Although the dialogs are nonmodal, they appear to be modal to the user, unless an action occurs that must pre-empt the dialog.)
This is implemented in the TUI using the CVoIPDesktopManager::StartMessageBox method. To display a message box, code calls StartMessageBox. This method creates the message box and returns immediately.
If the message box returns normally (for example, if no call is made or received and the user has pressed one of the displayed message box buttons) the CVoIPDesktopManager, in the CVoIPDesktopManager::ReturnFromCurrentMessageBox method, sends a VDM_DLG_MESSAGEBOXRETURN message.
For more information about CVoIPDesktopManager, see CVoIPDesktopManager. For more information about how the TUI handles UI events, see Handling TUI User Input.
See Also
Examining the TUI Implementation
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