4. Messages - Messages and system input and output

Several functions are provided in order to receive and submit system messages, i.e. messages to be displayed in an output area or in a status or progress bar. In order to display those messages in a proper place in the application, the application may set an application context (typically the ProjectContext) by calling Application::context(). In order to redirect messages submitted by SystemClass functions to the proper output area of the application, the context assigned as system context should overload the subsequent functions:

• input - receive data from user input (input())
• output - write message to standard output area(SystemClass::Message(), output())
• startProgress - initialize progress display (startProgress())
• displayProgress - display progress state (displayProgress())
• stopProgress - deinitialize progress display stopProgress())
• statusMessage - show message on status line (statusMessage())

Those functions allow submitting messages by calling the appropriate SystemClass functions