I am thinking about getting an external LCD screen. I know our PBs can do the mirroring (PB's screen and external one showing the same image). But, can I use the external LCD screen without closing PB. I don't want to close and open my PSs' screens because I herad it may cause wear and tear of the hinges (I know I am very anal about this). Can I just shut off my PB's screen and use the external one without closing my PB?