The DC that was allocated on the CreateBufferRegionARB call is saved and used for subsequent save and restore operations. It must remain valid during the life of the buffer region. In keeping with the same paradigm as SwapBuffers, a flush will be made by the driver for the RC bound to the calling thread before the save and restore operations. This extension adopts the same philosophy. A buffer region can be created with wglCreateBufferRegionARB which returns a handle associated with the buffer region.
Positive values identify overlay planes, negative values identify underlay planes.
A value of 0 identifies the main plane. is a bitwise OR of any of the following values indicating which buffers can be saved or restored. Multiple bits can be set and may result in better performance if multiple buffers are saved or restored. When wglCreateBufferRegionARB fails to create a buffer region, a value of NULL is returned. To get extended error information, call GetLastError. The DC specified when the region was created is used as the device context specifying the window. and specify the window position for the source rectangle. and specify the width and height of the source rectangle.