R help - Apr 2007 - Write text in the "device region" of a graphic device

Hello,
I started a graphic device:
>par(oma = c(2,0,0,0), mfrow=c(2,2) )
in the cols and rows are three "image"s.
Now I want to write a text in the "device region", it's the
main title of the graphic device. But when I use "mtext()" I can
only write in the "figure region" of my four plots.

Has anybody an idea?

Thanks a lot.

Felix



My R Code:
----------
par(oma = c(2,0,0,0), mfrow=c(2,2) )

mtext("Main title", side = 3, line = 0)

image(zDIV)
image(zMEDIAN )              
image(zMEAN) 
image(zSD)  
dev.off() 



graphic:   

-------------------------------------------
|	MAIN TITLE   device region	   
-------------------------------------------
|   figure region    |   figure region    |
|  --------------    |    ------------    |
|  |		|    |	  |	     |	  |
|  |		|    |    |	     |    |
|  |		|    |	  |	     |	  |
|  |		|    |    |	     |    |
|  --------------         ------------    |
|					  |	      
-------------------------------------------
|   figure region    |   figure region    |
|  --------------    |    ------------    |
|  |		|    |	  |	     |	  |
|  |		|    |    |	     |    |
|  |		|    |	  |	     |	  |
|  |		|    |    |	     |    |
|  --------------         ------------    |
|					  |