Instant apply windows

[Sami Wagiaalla <swagiaal at redhat dot com>]

Instant apply utility windows refer to windows which change the settings 
of an application instantly. The do not have [OK] and [Cancel] buttons 
only a [close] button.

Which type of windows should be used for settings of observers, and 
sessions ?

The hig recommends always using instant apply windows except when:
 - the changes can take more than 1 second to apply.
 - the changes must be applied simultaneously.

While both above reasons do not apply to the Observer and Session 
Editing windows. It can be argued that the changes are kind of high 
risk, and they may have an effect on the performance of the user's 
system. So it is important the request that they explicitly click [OK].

Thoughts ??