Option "revert button layout" is only showed when gconf key "/apps/metacity/general/button_layout" is unset or it's value differs from the button layouts of both new (selected) and previous themes. So this happens if you have a custom value for this key or on upgrade.
Option "revert button layout" is only showed when gconf key "/apps/ metacity/ general/ button_ layout" is unset or it's value differs from the button layouts of both new (selected) and previous themes. So this happens if you have a custom value for this key or on upgrade.