'Grob' class is a container for 'grob' based object defined with grid
system. Generic function Grob gets grob object supported by grid system, and make an instance of
subclass of class 'Grob'.
'GrobList' is a container of list of 'Grob' object.
Usage
"Grob"(x)
"Grob"(x)
"Grob"(x)
"Grob"(x)
"Grob"(x)
Arguments
x
object of class: gg, gtable, trellis, lattice, GGbio.