Your driver receives ICM_DRAW_END when the client-application no longer needs data decompressed or rendered. For this message, your driver should free the resources it allocated for the ICM_DRAW_BEGIN message. Your driver should also leave the display in the full screen mode.
After sending ICM_DRAW_END, the client-application must send ICM_DRAW_BEGIN to continue decompressing data. Your driver should not expect the client-application to send a ICM_DRAW_END message for each ICM_DRAW_BEGIN message. The client-application can use ICM_DRAW_BEGIN to restart decompression without sending ICM_DRAW_END.