Comment 2 for bug 141210

For the meantime you can change you workspace layout using any of the following three methods:

1.) gconf-editor
  start gconf-editor via a gnome-terminal or via Alt-F2
  in the tree-structure on the left side of the newly opened window locate...
    /apps/compiz/general/screen0/options/
  on the right side - in the scrollable view - locate entries...
    vsize
    hsize
  change them to your liking by double-clicking the respective entry and alter the value

2.) gconftool-2 (as an example we set up a 4:2 workspace layout)
  start a gnome-terminal
  enter the commands...
    gconftool-2 -s -t int /apps/compiz/general/screen0/options/vsize 4
    gconftool-2 -s -t int /apps/compiz/general/screen0/options/hsize 2

3.) ccsm/compiz-config-settings-manager (not installed by default)
  start ccsm via a gnome-terminal or via Alt-F2
  go to the 'General' section (click the button at the top of the scrollable view on the right)
  go to the 'Desktop Size' tab
  set horizontal and vertial size to your liking
  _leave_ number of desktops at 1