class = "w_opt"

format=0

radio buttons (default format)

format=1

text/icon buttons

format=2

buttons on "options" popup menu

row=num

no. of rows

col=num

no. of columns (ignored for format=2)

width=num

button width in unit spacing (for format=0,1)

non_exc

non-exclusive buttons (default is exclusive)

vert

label is above the options (default) OR...

horz

label is to the right of the options

label:command

label/command-string pair (command may be undefined, but still put ':' after label)

icon

icon labels (default is text labels)

align=r,c,l

alignment for buttons, r=right, c=center (default), l=left (for format=1)