Set @PESH=0 to disable book comment tooltip.
Set @PESS=-1 to show preview as Comments-style tooltip.
In the past, X will close PE and sometimes user doesn't know how to turn it on. So we changed the default behavior to be Hide PE if it's unpinned.
System Variable @FDPC to control this:
0 : old way, close1 : most logical way, Hide if unpinned (default)2 : stronger way, Hide always
vector Movrms(vector vx, int back[, int forward])