Override open/save dialogs globally

Hi all,

I need to know if there is a way to customise the Windows Open/Save dialogs at a global level (i.e; for *every* application).

I know I can 'subclass' CommonDialog controls or use Windows API + Callbakcs to customise the dialogs within my own application.
But what I really want to do is customise these dialogs for all Windows applications.

Have investigated a windows message hook for messages to launch the dialog, and take it from there, but I can't find anything common about the dialogs even just between Word and Excel for example...

Any thoughts welcome...