popup.show........

I am using a popup element and its show method. I know it takes 5
arguments.
popup.show(x,y,width,height,element)
I want to show a popup starting from the right hand (doesn't matter top
or bottom)corner of the screen.
I am specify the argument x=0.
I works fine with ordinary screens but gets chopped off for flat
screens.
How do I make it work?
and also irrespective of the screen I use how do I specify the
arguments so that the popup starts from the right hand corner of the
screen?
can someone throw some light on this thanks.