Thank you for taking the time to report this bug and help make Ubuntu better. From what I understand, you seem to have a problem with Alt+Right Click being mapped to activate the window menu, and not being user configurable. If that is the case, then this is not an issue with gconf-editor or gconf, but an issue with Metacity itself. What you want is for Metacity to make this keybinding configurable and expose it through GConf.
Thank you for taking the time to report this bug and help make Ubuntu better. From what I understand, you seem to have a problem with Alt+Right Click being mapped to activate the window menu, and not being user configurable. If that is the case, then this is not an issue with gconf-editor or gconf, but an issue with Metacity itself. What you want is for Metacity to make this keybinding configurable and expose it through GConf.