Ideas

[V-Man]

Combination select:

/addtoselection x y xs ys
/subfromselection x y xs ys

In theory, would this cause a selection to be able to leave the limits of rectangularity?

Translate the selection(Not the cubes selected but the selection box itself):

/transselect x y

If I read your request correctly, I think this script should do what you want. Can't remember if it's in the latest tools.cfg or not, but it'll be in the next one for sure.

[SELECT ALL] Code:

// shiftsel -- Takes the current selection and moves it a given amount -- by V-Man
// Can take integers representing (x, y) coordinates or characters representing cardinal directions.
alias shiftsel [
if (isint $arg1) [
selx (+ $selx $arg1)
sely (+ $sely $arg2)
] [
if (strcmp $arg1 "N") [sely (- $sely $arg2)] [
if (strcmp $arg1 "S") [sely (+ $sely $arg2)] [
  if (strcmp $arg1 "E") [selx (+ $selx $arg2)] [
   if (strcmp $arg1 "W") [selx (- $selx $arg2)] [echo (c 3)Integers and cardinal directions only! N, S, E, W]]]]
if (strcmp $arg3 "N") [sely (- $sely $arg4)] [
if (strcmp $arg3 "S") [sely (+ $sely $arg4)] [
  if (strcmp $arg3 "E") [selx (+ $selx $arg4)] [
   if (strcmp $arg3 "W") [selx (- $selx $arg4)] [echo (c 3)Integers and cardinal directions only! N, S, E, W]]]]]]
// shiftsel 2 4
// shiftsel E 2 S 4