Call GPM "Inhibit" methods when the machine is busy but there is no user activity

Gnome Power Manager has a preference allowing the user to have their machine suspend or hibernate after the machine has been idle for a certain time. The difficulty is that a lack of mouse or keyboard activity does not necessarily equate to "session not in use" and the machine may suspend when it is undertaking a long task (e.g. copying large files) or performing an activity requiring no input from the user (e.g. playing music). GPM has "Inhibit" DBUS methods to prevent suspending in this case.