This happens in 12.04 too. It now looks like the string "toggle-maximize-vertically" is being put into gconf. The dashes should be underscores though; correcting it to "toggle_maximize_vertically" makes things work as expected.
This happens in 12.04 too. It now looks like the string "toggle- maximize- vertically" is being put into gconf. The dashes should be underscores though; correcting it to "toggle_ maximize_ vertically" makes things work as expected.