This is a (for lack of a better name) hypertext widget.

This widget combines text and other Tk widgets in the same window.
It is sort of a cross between a read-only text widget and the pack command.
Any widget can be attached to the hypertext window by the %% 
set this $htext(widget)
label $this.lab -text "append " -relief sunken \
        -font *-Courier-Bold-R-Normal-*-12-120-*
$this append $this.lab 
%% command.
For example,
%% message $this.msg -relief sunken -bd 2 -aspect 10000 -font \
 *-Courier-Medium-R-Normal-*-12-* -text {set w $htext(widget)
label $w.face -bitmap @bitmaps/face.xbm \ 
  -relief sunken -borderwidth 2
$w append $w.face -padx 2 -pady 0.25i}
$this append $this.msg \
        -fill both %% added this %%
global tk_library
label $this.face \
        -bitmap @bitmaps/face.xbm  \
        -relief sunken -borderwidth 2
$this append $this.face -padx 2 -pady 0.25i 
%%.
There can be many types of widgets in the same document.  For example,
this is a simple %% 
button $this.but -bg pink -text { button } \
  -command { puts stderr { a stupid message } } 
$this append $this.but 
%%. If you click on the button, it prints a stupid message.
Any Tk widget can be used, including %%
set whichTile 0
proc ChangeTile { w } {
   global whichTile

   if { $whichTile } {
        $w configure -tile bgTexture2
   } else {
	$w configure -tile bgTexture1
   }
}
checkbutton $this.ckbut -bg lightblue -text { check buttons } \
   -variable whichTile -command "ChangeTile $this" 
$this append $this.ckbut -justify top
%%, %%
radiobutton $this.rdbut -bg mediumseagreen -text { radio buttons } \
        -command { puts stderr { radio button pressed } } 
$this append $this.rdbut -justify bottom
%%, 
and scales %%
# -sliderforeground
scale $this.sc -showvalue true \
        -length 100 \
        -foreground powderblue \
        -sliderlength 10 \
        -orient horizontal  
$this append $this.sc
%%.

        Widget trees can be also be included. The following example is
*borrowed* from the widget demo. It is a couple of frames surrounding a
listbox, a message, and a button widget.
%%
    set w $this.frame 
    frame $w 
    message $w.msg -font *times-medium-r-normal--*-12-120-* -aspect 300 \
            -text "A listbox containing the 50 states is displayed below, along with a scrollbar.  You can scan the list either using the scrollbar or by dragging in the listbox window with button 3 pressed.  Click the \"OK\" button when you've seen enough." -bg lightsteelblue -relief sunken
    frame $w.frame -borderwidth 10 
    pack append $w.frame \
        [scrollbar $w.frame.scroll -relief sunken \
            -command "$w.frame.list yview"] {right expand filly frame w} \
        [listbox $w.frame.list -yscroll "$w.frame.scroll set" -relief sunken] \
            {left expand filly frame e}
    $w.frame.list insert 0 Alabama Alaska Arizona Arkansas California \
        Colorado Connecticut Delaware Florida Georgia Hawaii Idaho Illinois \
        Indiana Iowa Kansas Kentucky Louisiana Maine Maryland \
        Massachusetts Michigan Minnesota Mississippi Missouri \
        Montana Nebraska Nevada "New Hampshire" "New Jersey" "New Mexico" \
        "New York" "North Carolina" "North Dakota" \
        Ohio Oklahoma Oregon Pennsylvania "Rhode Island" \
        "South Carolina" "South Dakota" \
        Tennessee Texas Utah Vermont Virginia Washington \
        "West Virginia" Wisconsin Wyoming
    button $w.ok -text OK -command "puts stderr $w; destroy $w"

    pack append $w $w.msg {top fill} $w.frame {top expand fill} \
        $w.ok {bottom fill}
    $w config -bg lightsteelblue -relief sunken

$this append $w -pady 0.25i
%%

You can add you own home-grown widgets.  Here's the graph widget.
Beside it is the "color" demo.  Moving the scales, adjusts the background
color of the graph.
%%
#
# Simple script to change colors of a window.
#
global xlabel ylabel red green blue graph
set red 255
set green 215
set blue 0

option add *Scale.sliderForeground "#cdb79e"
option add *Scale.activeForeground "#ffe4c4"
set w $this.colorFrame
frame $w
scale $w.red -command "color red" -label "Red Intensity" \
        -from 0 -to 255 -orient horizontal -bg "#ffaeb9" -length 250
scale $w.green -command "color green" -label "Green Intensity" \
        -from 0 -to 255 -orient horizontal -bg "#43cd80"
scale $w.blue -command "color blue" -label "Blue Intensity"  \
        -from 0 -to 255 -orient horizontal -bg "#7ec0ee"

$w.blue set $blue
$w.green set $green
$w.red set $red

pack append $w $w.red {top expand fill}
pack append $w $w.green {top expand fill}
pack append $w $w.blue {top expand fill}

proc color {which intensity} {
    global red green blue graph xlabel ylabel
    set $which $intensity
    set rgb [format #%02x%02x%02x $red $green $blue]
    $graph config -bg $rgb
    $xlabel config -bg $rgb
    $ylabel config -bg $rgb
}

$this append $w 

%% 
%%
proc makeplot { widget } {

    graph $widget
    set X { 
        2.00000e-01 4.00000e-01 6.00000e-01 8.00000e-01 1.00000e+00 
        1.20000e+00 1.40000e+00 1.60000e+00 1.80000e+00 2.00000e+00 
        2.20000e+00 2.40000e+00 2.60000e+00 2.80000e+00 3.00000e+00 
        3.20000e+00 3.40000e+00 3.60000e+00 3.80000e+00 4.00000e+00 
        4.20000e+00 4.40000e+00 4.60000e+00 4.80000e+00 5.00000e+00 
    } 

    $widget element create Y1 -x $X -y { 
        1.14471e+01 2.09373e+01 2.84608e+01 3.40080e+01 3.75691e+01 
        3.91345e+01 3.92706e+01 3.93474e+01 3.94242e+01 3.95010e+01 
        3.95778e+01 3.96545e+01 3.97313e+01 3.98081e+01 3.98849e+01 
        3.99617e+01 4.00384e+01 4.01152e+01 4.01920e+01 4.02688e+01 
        4.03455e+01 4.04223e+01 4.04990e+01 4.05758e+01 4.06526e+01 
    } -symbol circle -label VGS=2.0 -color blue4 -fill blue

    $widget element create Y2 -x $X -y { 
        2.61825e+01 5.04696e+01 7.28517e+01 9.33192e+01 1.11863e+02 
        1.28473e+02 1.43140e+02 1.55854e+02 1.66606e+02 1.75386e+02 
        1.82185e+02 1.86994e+02 1.89802e+02 1.90683e+02 1.91047e+02 
        1.91411e+02 1.91775e+02 1.92139e+02 1.92503e+02 1.92867e+02 
        1.93231e+02 1.93595e+02 1.93958e+02 1.94322e+02 1.94686e+02 
    } -symbol diamond -label VGS=3.5 -color green4 -fill green

    $widget element create Y3 -x $X -y { 
        4.07008e+01 7.95658e+01 1.16585e+02 1.51750e+02 1.85051e+02 
        2.16479e+02 2.46024e+02 2.73676e+02 2.99427e+02 3.23267e+02 
        3.45187e+02 3.65177e+02 3.83228e+02 3.99331e+02 4.13476e+02 
        4.25655e+02 4.35856e+02 4.44073e+02 4.50294e+02 4.54512e+02 
        4.56716e+02 4.57596e+02 4.58448e+02 4.59299e+02 4.60151e+02 
   } -symbol triangle -label VGS=5.0 -color red4 -fill red

}

option add *graph.title  "Plot Title" 
option add *graph.xTitle "X Axis Label"
option add *graph.yTitle "Y Axis Label" 
#option add *graph.legendMapped false 
option add *graph.elemPixels 8
option add *graph.relief ridge
option add *graph.borderWidth 2

set graph $this.graph
set xlabel $this.xlab
set ylabel $this.ylab
makeplot $graph
$this append $graph -padx 0.25i -pady 0.25i 

%%
If you click on any button in the graph, you will get the coordinate 
values at the pointer location.  

The current coordinate values are %%
label $xlabel -text { ??? ??? } -relief sunken
label $ylabel -text { ??? ??? } -relief sunken
bind $graph <ButtonPress> {labelxy [ %W invtransform %x %y ]}

proc labelxy { values } {
    global xlabel ylabel
    scan $values "%e %e" x y
    $xlabel config -text $x
    $ylabel config -text $y
}
$this append $this.xlab -width 100 -fill x
%% and %%
$this append $this.ylab -width 100 -fill x
%%.


There are four global variables automatically created when a hypertext
file is read. They are:

%% 
button $this.l1 -text " \$htext(widget) " \
	-command "puts $this" -bg orange
$this append $this.l1 -width 200 -pady 4
%%the pathname of the hypertext widget. 
%% 
button $this.l2 -text " \$htext(file) " \
	-command "puts $htext(file)" -bg orange
$this append $this.l2 -width 200 -pady 4
%%the file being read.
%% 
button $this.l3 -text " \$htext(line) "  \
	-command "puts $htext(line)" -bg orange
$this append $this.l3 -width 200 -pady 4
%%the current line number.
%% 
button $this.l4 -text " \$htext(index) " \
	-command "puts $htext(index)" -bg orange
$this append $this.l4 -width 200 -pady 4
%%the current index in the text.

Click on any button and the current value is printed on standard output.

The hypertext widget works with plain text too. If you don't want
to read it, click on the %% 
button $this.goto -text button -fg purple -bg white \
        -command "global endOfText; $this gotoline \$endOfText"
$this append $this.goto
%% to jump to the end of the plain text.

         ------------------------------------------------------

[This is a pre-release version of BLT.  It's basically the latest

snapshot of BLT, as it moves towards a full release.  What this means
is that the documentation and demos still need work.  Let me know
about any configuration/compiler/installation goofs so I make sure
they're fixed for the next release.]

This is version 2.4 of the BLT library.  It's an extension to the
Tcl/Tk toolkit.  You simply compile and link with the Tcl/Tk
libraries. It does not require the Tcl or Tk source files.

BLT is available from 

    ftp.tcltk.com 

in the "pub/blt" directory. The URL is 

    ftp://ftp.tcltk.com/pub/blt/BLT2.4.tar.gz

This release has been compiled and tested with versions:

        Tcl 7.5 / Tk 4.1
        Tcl 7.6 / Tk 4.2
        Tcl/Tk 8.0
        Tcl/Tk 8.1a2

What is BLT? 

  BLT is an extension to Tk.  It adds plotting widgets (X-Y graph, 
  barchart, stripchart), a powerful geometry manager, a new canvas 
  item, and several new commands to Tk.  

  Plotting widgets:  

    graph, barchart, stripchart
                BLT has X-Y graph, barchart, and stripchart widgets that are
                both easy to use and customize.  All the widgets work with
                BLT vector data objects, which makes it easy to manage data.
 
  Hierarchical list box:

    hierbox     Displays a general ordered tree which may be built 
                on-the-fly or all at once.

  Tab set:

    tabset      Can be used either as a tab notebook or simple tabset.
                Multi-tiered and/or scrolled tabsets are available.
                Notebook pages can be torn-off into separate windows and 
                later put back. 
    
  Geometry Manager:  

    table       A table-based geometry manager. Lets you specify widget
                layouts by row and column positions in the table. Unlike the
                packer or grid, you can finely control and constrain window
                sizes.

  Vector Data Object:

    vector      Lets you manage a vector of floating point values in a
                high-level fashion.  Vectors inter-operate seamlessly with 
                the plotting widgets. The graphs will automatically redraw 
                themselves when the vector data changes. Vector's components 
                can be managed through a Tcl array variable, a Tcl command, 
                or the using its own C API.

  Background Program Execution:

    bgexec      Like Tcl's "exec ... &", but collects the output, error, and 
                status of the detached UNIX subprocesses.  Sets a Tcl variable 
                upon completion.  

  Busy Command:

    busy        For preventing user-interactions when the application is
                busy.  Manages an invisible "busy" window which prevents
                further user interactions (keyboard, mouse, button, etc.).
                Also you can provide a busy cursor that temporarily 
                overrides those of the Tk widgets.

  New Canvas Item:

    eps         An new item is added to the Tk canvas for handling
                encapsulated PostScript.  It lets you embed an EPS file into
                the canvas displaying either an EPS preview image found in 
                the file, or a Tk image that you provide.  When you print 
                the canvas the EPS item will automatically include the EPS 
                file, translating and scaling the PostScript.  For example, 
                you could use "eps" items to tile several PostScript pages 
                into single page.

                The "eps" item can also be used as a replacement for "image"
                canvas items.  Unlike "image" canvas items, the image of an 
                eps item can be printed and scaled arbitrarily.

  Drag & Drop Facility:

    drag&drop   Adds drag-n-drop capabilities to Tk.  It uses "send"-style 
                communication between drag-drop sources and targets.  The 
                result is a much more powerful drag-and-drop mechanism than 
                is available with OpenLook or Motif.  

  Bitmap Command:

    bitmap      Lets you read and write bitmaps from Tcl.  You can define
                bitmaps from ordinary text strings.  Bitmaps can also be
                scaled and rotated.  For example, you can create a button
                with rotated text by defining a bitmap from a text string
                and rotating it.  You can then use the bitmap in the button
                widget.

  Miscellaneous Commands:

    winop       Basic window operations. You can raise, lower, map, or, 
                unmap windows.  Other operations let you move the pointer
                or take photo image snapshots of Tk widgets.

    bltdebug    Lets you trace the execution of Tcl commands and procedures.
                Prints out each Tcl command before it's executed.  

    watch       Lets you specify Tcl procedures to be run before and/or
                after every Tcl command.  May be used for logging, tracing, 
                profiling, or debugging or Tcl code.

    spline      Computes a spline fitting a set of data points (x and y 
                vectors) and produces a vector of the interpolated images 
                (y-coordinates) at a given set of x-coordinates.

    htext       A simple hypertext widget. Allows text and Tk widgets to
                be combined in a scroll-able text window.  Any Tk widget 
                can be embedded and used to form hyper-links.  Other 
                options allow for selections and text searches.

What's new in 2.4?

 1. "eps" canvas item.  

    An encapsulated PostScript canvas item lets you embed an EPS file into 
    the canvas.  The "eps" item displays either a EPS preview image found 
    in the file, or a Tk image that you provide.  

 2. "hierbox" widget.

    Hierarchical listbox widget. Displays a general ordered tree which 
    may be built on-the-fly or all at once.

 3. "tabset" widget.

    Can be used either as a tab notebook or simple tabset.  Tabs can 
    be arranged in a variety of ways: multi-tiered, scrolled, and 
    attached to any of the four sides.  Tab labels can contain both 
    images and text (text can be arbitrarily rotated). Notebook pages 
    can be torn-off into separate windows and replaced later. 
    
 4. Changes to vectors.

    New features:
        
     o  Vector expressions.  The vector now has an "expr" operation
        that lets you perform math (including math library
        functions) on vectors.  There are several new functions
        (such as "max", "min", "mean" "median", "q1", "q3", "prod",
        "sum", "adev", "sdev", "skew", ...)

                vector expr { sin(x)^2 + cos(x)^2 }
                y expr { log(x) * $value }

     o  New syntax to create and destroy vectors:

                vector create x 
                vector destroy x
 
        The old syntax for creating vectors still works.

                vector x

     o  Vectors are *not* automatically deleted when their Tcl
        variable is unset anymore. This means that you can
        temporarily map vectors to variables and use them as you
        would an ordinary Tcl array (kind of like "upvar").

            proc AddValue { vecName value } {
                 $vecName variable x
        
                 set x(++end) $value
            }   

        There's an "-watchunset" flag to restore the old
        behavior if you need it. 

            vector create x -watchunset yes

     o  Vectors still automatically create Tcl variables by
        default.  I'd like to change this, but it silently
        breaks lots of code, so it will stay.

    Bug fixes:

     o  Vector reallocation failed when shrinking the vector.

     o  Vector "destroy" callback made after vector was
        already freed.

 5. Changes to Graph, Barchart, Stripchart widgets.

    New features:

     o  Drop shadows for text (titles, markers, etc). Drop
        shadows improve contrast when displaying text over a
        background with similar color intensities.
   
     o  Postscript "-preview" option to generate a EPS
        PostScript preview image that can be read and
        displayed by the EPS canvas item.

     o  New "-topvariable", "-bottomvariable",
        "-leftvariable", and "-rightvariable" options.  They
        specify variables to contain the current margin
        sizes.  These variables are updated whenever the
        graph is redrawn.

     o  New "-aspect" option. Let's you maintain a particular aspect
        ratio for the the graph.

     o  Image markers can now be stretched and zoomed like
        bitmap markers.

     o  Bind operation for legend entries, markers, and elements.

        Much thanks to Julian Loaring <bigj@bigj.demon.co.uk> 
        for the suggestions.

     o  New "-xor" option for line markers, lets you draw the line
        by rubberbanded by XOR-ing without requiring the graph to
        be redrawn.  This can be used, for example, to select regions
        like in zooming.  

        Thanks to Johannes Zellner (joze@krisal.physik.uni-karlsruhe.de) 
        for the suggestion.

    Bug fixes:

     o  Closest line (point) broken when using pens styles.

     o  Marker elastic coordinates were wrong.

     o  PostScript bounding box included the border of the page.

     o  Bad PostScript generated for barchart symbols with stipples.

     o  Wrong dimensions computed with postscript " -maxpect" option.

     o  Text markers fixed.

        Thanks to De Clarke for the bug report and fix.


     o  Renamed axis configuration from "-range" to "-autorange" to
        match the documentation.  

        Thanks to Brian Smith for the correction.

     o  Fixed polygon marker pick routine.

     o  Fixed active tab labels overlapping the selected tab.


What's incompatible with releases prior to BLT 2.4?

 1. Vector names must start with a letter and contain letters, digits,
    or underscores.  

    Namespace Issues:   Vector names are still global. If Tcl provides
                        an API, vectors may in the future be created on
                        a per-namespace basis.  Right now, there's no
                        mechanism for detecting when a namespace has been
                        destroyed. Which is why you can't currently
                        prefix a vector name with a namespace qualifier.

                        [Ok, there is... Thanks to Michael McLennan for
                        pointing this out to me.  So maybe soon there 
                        will be vectors on a per namespace basis.]
        
 2. The "-mapped" options throughout the graph have been replaced
    by the "-hide" option.  The many usages of the word "map" was 
    getting confusing.  

        # No longer works.
        .graph legend configure -mapped no

        # Instead use this.
        .graph legend configure -hide yes    
 
   
How to compile and test BLT?

  See the file "INSTALL" for instructions.

When will the so-called "official" BLT work with Windows?  

  It currently compiles and runs with MS VC++ and EGCS 1.1 under 
  Windows 95/NT (loadable binary versions will be forthcoming).  
  Everything pretty much works: graphs, bgexec, busy, drag&drop etc.
   
When will...?

  In general, I can't answer the "When will" questions, mostly out of 
  embarrassment.  My estimates of when new features and releases will
  occur usually turn out to be way way off.  

What does BLT stand for?

  Whatever you want it to.

--gah

%%
global endOfText
set endOfText [expr $htext(line)-1 ]

global updateInterval count barchart
global Red Green Blue
set updateInterval 200
set count 0
set Red bb
set Green 00
set Blue 33

option add *barchart.title "Bar Chart" 
option add *barchart.x.title "X"
option add *barchart.y.title "Y"
option add *barchart.y2.title "Y"
option add *barchart.Axis.subTicks 0
option add *barchart.x.stepSize 0
option add *barchart.x.Ticks 0
option add *barchart.legend.hide yes
option add *barchart.Axis.Font *-Courier-Bold-R-Normal-*-8-80-* 
option add *barchart.y2.hide yes

set barchart $this.barchart
barchart $barchart -bd 2 -relief raised  -tile bgTexture2
$barchart y2axis use y
$this append $barchart -fill both -padx 10 -pady 10 -relwidth 0.8

proc AnimateBarchart {  } {
    global updateInterval
    global barchart count Red Blue Green
    
    if { [info commands $barchart] != $barchart } {
        return
    }   
    incr count
    if { $count > 100 } {
        $barchart element delete [lindex [$barchart element show] end]
    }
    set color [format "%x" [expr $count%16]]
    set Green ${color}${color}
    $barchart element create $count -data { $count sin($count*0.1)} \
        -fg #${Red}${Green}${Blue} -bg brown 
    after $updateInterval AnimateBarchart
}
AnimateBarchart

%%

        Press %%
button $this.quit -command { exit } -text {Quit} -bg pink
$this append $this.quit
%% to remove the window.