DISJOINT.TK v1.3	- by Paul Raines

The file disjoint.tk contains code for a "listbox" using the text
widget that supports disjoint selection and line by line configuration
of color, font, etc.  The main losses are the horizontal scrollbar and
selection speed.  The included file disjoint.test demonstrates the use
of the library.  For the most part, you can replace your normal
'listbox' command with 'disjointlistbox' with the following provisos

	(1) Configuration options are those of the text
	    widget instead of the listbox widget. This means
	    that the following listbox options aren't supported
		 geometry (use width and height instead)
		 xscrollcommand (sorry, can't do it)
		 exportselection (not with disjoint selection)
            The following option is also defined
	         selectrelief (for relief of selection tag)

        (2) All the normal widget methods are implemented except
	    xview and select adjust. Also, in the scan mark and
	    scan dragto methods, the x coordinate is ignored.

	(3) The following commands have been expanded.
	      curselection ?offset?
		  - offset is added to each index before the
		    list of selected indices is returned. This
		    is mainly there to make my life easier in TkMail
	      select clear ?index?
	          - where if index is given, only the item
		    at that position will be cleared
	      select from index ?keep?
		  - the key word 'keep' prevents other item
		    selections from being cleared. Index is
		    also made the primary single selection.
	      select to index ?keep?
		  - the key word 'keep' prevents other item
		    selections from being cleared
	      destroy
	          - safely destroy the disjoint listbox widget
		    ('destroy list' will seem to work but leaves
		     phantom procedures in memory)

	(4) The following commands have been added
	      cursingle
	          - returns the index of the primary single
		    selection marked with a ">". This features
		    makes the listbox into a single selection
		    and multi-selection box all-in-one.
	      scan at index
	          - select the item at index not clearing any
		    other item and only making index the primary
		    single selection if it is the only selection.
	      select toggle index
	          - toggle the selection state of item at index 
		    not clearing any other item
	      item configure index ?option value ...?
	          - lets you configure a single line of the list
		    as a text tag. See the text widget tag configure
		    command for valid options.
	      item clear index ?index ...?
		  - clear configuration on a list item made
		    with the item configure command.

NOTE: be careful not to include any "\n" characters in
	lines of text inserted into the disjoint listbox.
	This will really screw things up.

The default bindings are:

	<1>	Clicked item becomes "first" and only
		selected item
<Shift-1>	Toggle items selection
	<2>	Scanning
	<3>	Clicked item becomes an additional 
		selected item
<Shift-3>	Clicked item becomes is deselected

<1>, <3>, & <Shift-3> can be dragged to select (or deselect)
additional items, however, only <1> uses anchoring so that
you can backtrack.

COPYRIGHT:
    Copyright 1994 by Paul Raines (raines@bohr.physics.upenn.edu)

    Permission to use, copy, modify, and distribute this
    software and its documentation for any purpose and without
    fee is hereby granted, provided that the above copyright
    notice appear in all copies.  The University of Pennsylvania
    makes no representations about the suitability of this
    software for any purpose.  It is provided "as is" without
    express or implied warranty.

DISCLAIMER:
    UNDER NO CIRCUMSTANCES WILL THE AUTHOR OF THIS SOFTWARE OR THE
    UNIVERSITY OF PENNSYLVANIA BE RESPONSIBLE FOR ANY DIRECT OR
    INCIDENTAL DAMAGE ARISING FROM THE USE OF THIS SOFTWARE AND ITS
    DOCUMENTATION. THE SOFTWARE HEREIN IS PROVIDED "AS IS" WITH NO
    IMPLIED OBLIGATION TO PROVIDE SUPPORT, UPDATES, OR MODIFICATIONS.