Processes events from the internal message queue.
When DoEvents is called, the class processes any available events. If no events are available, it waits for a preset period of time, and then returns.
This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)