Extending the default Page controller

Summary

Extending the behaviour of the default page controller

Content

Hi all,

I have some business logic I need to implement in all of my CP pages.  The logic is to check Service Cloud for a maintenance config flag, and retrieve a MessageBase if the flag has been set.  If there is the flag set, the pages will then instantiate a widget which does the actual display of the MessageBase.  If there is no config flag set, the page will render as normal.

Rather than putting the code in a library, and then copy pasting a php call to the method on every page, I'd like to do the check and have the controller pass the outcome to the CP page, who will then action that.