Bargraph

Bargraph is one of Pablo's display functional units.  It represents its 
input parameter as a single bar whose size varies with the magnitude of the
incoming datum.  Bargraph scales the bar according to a "minimum" and a
"maximum" data value kept within the functional unit.  The minimum and maximum 
values may be set by the user during the configuration process.

In addition to the bar, Bargraph maintains a "sticky hold" value -- a line
drawn in color to mark the maximum value the bar has obtained during a 
given period.  This time interval can be set during the configuration process;
the value specified is the number of previous updates that are considered
when determining the sticky value.

The bargraph can be represented as either a color-filled region or as a pixmap.

If the sticky hold resource is set to -1, no sticky value is shown.

Clicking the left mouse button with the cursor inside the bar invokes a 
callback displaying the current value of the bargraph and also its row and/
or column position (in the case of vector and array layouts).


Functional Unit Inputs:     scalar, vector, array

Bargraph attributes:	
  
	XtNheight	height (in pixels) of the bar
	XtNwidth	width (in pixels) of the bar
	XtNbackground	color of the widget background 
	XtNstickyHold	number of updates used as history for sticky hold 
	XtNstickyColor	color in which the sticky hold line is drawn
	XtNminValue	minimum data value represented by the widget
	XtNmaxValue	maximum data value represented by the widget
	XtNorientation	direction in which bar grows (vertical or horizontal)
	XtNfillColor	color of the bar
