The application can use this message to determine the size of either the notebook window or the application page window. It can also be used when the application handles the position and size of the application page window.

To calculate the application page rectangle, specify the coordinates of the notebook window in the pRectl parameter and TRUE in the bPage parameter. The notebook control then uses the coordinates specified in the pRectl parameter to calculate and return the coordinates of the application page window.

To calculate the notebook rectangle, specify the coordinates of the application page window in the pRectl parameter and FALSE in the bPage parameter. The notebook control then uses the coordinates specified in the pRectl parameter to calculate and return the coordinates of the notebook window.