I just bought a 23 inch apple monitor and attached it to my powerbook.
Everything seems to work fine *except* when I try closing the powerbook.
When I do, the system goes to sleep, and comes back to life when I tap
the power button on the side of the monitor, just like the salesman
showed.  However, at this point the cursor is no longer displayed.

I'm using an Apple wireless mouse.

I know the computer can still talk to the mouse, because I can still 
move the (invisible) cursor.  As I move the mouse, different things on
the screen become active, just as they should.  The system knows where
the cursor is; it just won't display it to me.

How do I fix this?