which of the 4 plot types to display. If more than one
are given they are shown in panels. The default is to show all 4.
Details
Note, this uses "user.text", which is not a standard element of
Lattice style. However, this falls back to "add.text" -- the
default used by panel.text() -- if not defined.
"user.text" is preferred to "add.text" for annotations
because the latter also applies to strip text and key text.