6.10 Z-order functions

The z-order is an ordering of GOs in one page which represents the depth in which the GOs are situated. So, if GO1 is in front of GO2, then GO1 is z-lesser than GO2.

Comparisions

(z<=? x1 x2)
go go -> boolean

(z>=? x1 x2)
go go -> boolean

(z<? x1 x2)
go go -> boolean

(z>? x1 x2)
go go -> boolean

Reordering

(z-move-top! go)
go -> boolean
Moves the go on the top in its current group. Returns whether any real movement happened.

(z-move-up! go)
go -> boolean
Moves the go one step up in its current group. Returns whether any real movement happened.

(z-move-down! go)
go -> boolean
Moves the go one step down in its current group. Returns whether any real movement happened.

(z-move-bottom! go)
go -> boolean
Moves the go to the bottom in its current group. Returns whether any real movement happened.