now i found another question is that ,when i change the HDMI output display resolution(1080p->1080p) ,the DVI output screen will also flash a time although the DVI output resolution is not changed,so why?
but then i change the DVI output resolution (devId =1) to be 720p,that video output from DVI will not fill all the screen .
but if at the begin i just change the DVI output resolution ,not set the HDMI ,the video output from DVI will fill all the screen.
so why set the HDMI resolution firstly ,then it will affect the dvi output fill all the screen ?