I have a MacBook Pro running 10.8.3. I have one external monitor plugged in, and the MacBook is largely stationary because it is a work computer.
When I go home for the night, I lock the screen, turn off the monitor, and close the laptop (I often have things running into the evening or overnight, hence no sleep or shutdown). When I arrive in the morning, I open the laptop and turn on the monitor, and all the windows are gathered on the laptop screen.
I'm assuming what happens is that when I close the laptop, the OS decides that only the external monitor is an available display, makes it primary, and moves everything there, and then when the laptop opens it repositions everything to the "new" primary display.
What I Want
I want to be able to close the lid of my laptop, open it again, and have all of my windows be where I left them, all while leaving my external monitor plugged in. Is that possible?