Link points<->points
Link lines<->lines
Link points<->lines

These first three control the coordination of linked brushing
between a pair of XGobis.  **If linking isn't working, make sure
the menus of the sending and receiving XGobi are in agreement.**

Link points<->points:
  When a pair of XGobis have the same number of rows *or*
  have the same value of `fname.nlinkable', then brushing
  case j in one will cause case j in the other to be 
  painted as well.  

  This will apply to color, glyph, or erasing if they are on.
  The functions on the Erase Menu are also linked across points.

Link lines<->lines:
  When a pair of XGobis have the same number of lines, 
  then color brushing line j in one will cause line j in
  the other to be colored as well.  (Glyph and erase
  brushing are undefined for lines.)

Link points<->lines:
  Now we're getting tricky.  When one XGobi has the same
  number of points that another has lines, then they can
  be linked for points->lines and lines->points brushing.
  (Again, glyph and erase brushing are undefined.)

Note:  If you find that the response is too slow, make sure the
receiving XGobi isn't doing any more work than necessary.  It
does the least work in XYPlot, Plot1D, or paused in Rotate or Tour;
it works pretty hard in Identify, Brush, or Scale.

Link color brushing
Link glyph brushing
Link erase brushing

These variables can be set in the XGobi resource file.  The defaults
are:

*linkGlyphBrush: True
*linkColorBrush: True
*linkEraseBrush: True