Under smart refresh, the system provides dynamic backup of obscured sections of the layer. The graphics routines will automatically draw into these backup areas when they encounter an obscured part of the layer. The backup memory will be used to automatically update the display when obscured sections later become exposed. With smart refresh layers, the system handles all of the refresh requirements of the layer, except when the layer is made larger. When parts of the layer are exposed by a sizing operation, the application must refresh the newly exposed areas. The advantage of smart refresh is the speed of updating exposed regions of the layer and the ability of the system to manage part of the updating process for the application.. Its main disadvantage is the additional memory required to handle this automatic refresh.