
content of array choice:
1: <1|0> cycling/not cycling
2: <string> main group
3: <string> sub group
4: <integer> objtype of chosen part
5: <1|0> use marked/select target
6: <1|0> parts hidden/none hidden
7: <integer> z coordinate to build at
8: <1|0> show objtype in hex/decimal

return values of main gump
* values < -300
  1:      create
  2:      line
  3:      tile
  4:      ring
  5:      mark
  6:      unmark
  7:      (un)hide
  8-13:   nudge
  14-19:  set z coordinate
  20:     rectangles
  21:     floors
  22:     sets
  30:     delete
  31:     undo
  32:     save
  33:     load
  34:     clear design
  35:     read docs
  36:     show hex/decimal ID
  37:     quit
  38:     save in TXT format
  39:     calculate costs (works on SIGENA shard only)

* values < -200
  main group chosen

* values < -100
  sub group chosen

* values > 0
  part chosen
