If a window is of the Smart Refresh type, then the system will not only preserve those pixels which are actually on-screen, but it will save all obscured pixels that are within the current window's size. The system will refresh those parts of the window revealed by changes in the overlapping with other windows on the screen, without involving the application. However, any part of the window revealed through the sizing of the window must be redrawn by the application. Again, Intuition will notify the application through the IDCMP_REFRESHWINDOW event. Because the obscured areas are kept in off-screen buffers, Smart Refresh windows are refreshed faster than Simple Refresh windows are, and often without involving the application. Of course, for the same reason, they use more display memory.