php and javascript

hi,
I´m having problem with a javascript function, I need to open a window 
modal, with IE I use "showmodaldialog" but in mozilla doesn´t works,
I readed that I have to use "window.openDialog" but doesn´t works.
Did somebody use this in mozilla?, Can I make this another way?

I probed with "window.open" like a window modal and worked it, but how 
do I do to receive a parameters like showmodaldialog?
I need to make an alphabetic search?

I´m sorry for my english.... I speak spanish

thank