[R] set x11 as default plot

[Bunny, lautloscrew.com]

Dear all, 

I am looking for a a way to set x11 as a default plotting engine instead of quartz, which I had some troubles with. 
If I just called it, like x11() an x11 window pops up and plots every graph that is called since then. Though I do not want to invoke it manually. I mean I do not have to use quartz() either before plotting. 

Thx in advance for any suggestions! 

best 

matt