Screensaver Xserver functions ? activation, change and stop

I am using Xfree86 4.2.0 and 2.4.17 linux kernel on a specific board with
Ibm Ppc405 processor.

I will wish to know which are the Xserver functions which are called during
the first activation of the screensaver,  for each new screensaver display a
when a Xevent stop the screensaver.

I 'm using the default X screensaver (an X in different size) to start and
stop some other functions.

Thanks in advance for your time and your help !

Best regards,

Olivier Eribon

Email : [email protected]