get-extent in editor<%>
Gets the current extent of the editor's graphical representation.
The result is only valid when the editor is displayed (see
Basic Organization).
For text% objects, calling this method may force the recalculation of edlocation
information if a maximum width is set for the editor, even if the editor currently has delayed refreshing (see
refresh-delayed?).
( -> void
send an-editor get-extent w h)
w : boxed non-negative real number or #f
h : boxed non-negative real number or #f
The w box is filled with the editor's width, unless
w is #f.
The h box is filled with the editor's height, unless
h is #f.