Sometimes I'm responsible for maintenance of an application that includes such elements as
    pack [button .b1 -text Lion -width 10] [button .b2 -text Hippopotamus -width 10]
[[show picture here]]  Notice that there's a problem with this fragment; 'Hippopotamus' is 
truncated.  That's not a good thing.  Most immediately, it's because .b2 has been assigned a
width that's too small.  Generally in Tk it's OK to allow things to have default sizes; there are
a couple of legitimate reasons to assign manifest sizes, though, including [[... and ...--but 
people also mistakenly set sizes when ...]].
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'''[PWQ]''' ''''20 Dec 03'''' Can you give a real example of when the size of a [widget] (such as a label) need to be specifed. Without one my
comment is that this is completely unnecessary. Either you want the label to be shown in full or not. If not then the label text should be truncated before displaying. (ie Hippo...)
I get annoyed when I see TCL apps that people have '''assummed''' the width based on the font they have and it truncates on my display. This is the sort of bullsh*t that you get with [VB] applications.

I appreciate the interest.  Here are two model situations with which I struggle:
   * I want two [button]s to have the same width on-screen, although their -text-s differ.  How do I get a button to pad itself out so it's as wide as another button?  I'd love to know a way.
   * I have a [label] whose -text varies occasionally.  I need its width to be constant, so my layout doesn't jerk around; I also need for the width to be big enough to allow for all the -text-s that will occur.
Do you have good -width-free ways to code these?

[KPV] Both these situations are usually best handled by the 
[geometry manager]--[grid] is especially good at this. In the 
first case, either keep the [widget]s in the same column with 
property ''--sticky ew'' or use the columnconfigure ''-uniform'' 
property. This occasionally won't work when the widgers are in 
different gridding masters. In the second case, I usually design 
the GUI to have plenty of space reserved for such labels then 
have the geometry fill up the space completely (again with 
''-sticky ew'' or ''-expand 1 -fill x'').

Keith, thanks much for your help.  I'm still not getting the results I'm after.  I'll give more details.

The first situation is something like this:  the customer wants to 
see the second row of buttons in
    frame .f0
    frame .f1

    button .f0.b01 -text Simple
    button .f0.b02 -text Complicated
    button .f0.b03 -text Done

    button .f1.b01 -text Simple -width 10
    button .f1.b02 -text Complicated -width 10
    button .f1.b03 -text Done -width 10

    pack .f0 .f1    
    grid .f0.b01 .f0.b02 .f0.b03 
    grid .f1.b01 .f1.b02 .f1.b03
not the first.  How can I partition a row into equal-width elements without manifest
constants?  Yes, grid'll arrange buttons or labels into equally-wide cells, but it doesn't
expand the buttons out to fill those cells--at least, I don't know how to make that
happen.  I'd love a demonstration that there's a better way to use grid.  I'm all in favor
of letting geometry managers do their work, and I definitely do '''not''' aspire to VBishness.


[GPS]: It sounds as though you want to set the -weight of the (column/row)s which you want to grow.  Look into the rowconfigure and columconfigure subcommands to [grid].

[BBH]: If you have the cells of the grid like you want, you just need to add -sticky ew to make the widgets fill the cells. 15 Jan 2004  - you don't need any calculations use the -uniform option to
columnconfigure

    grid columnconfigure .f0 {0 1 2} -uniform 1

----
If those widths are constant values, they need to be correct ones.  Too-small labels make bad
impressions on users.  Here's a way I ask an application to tell me about itself:  I [source] in
    proc walker {w procedure} {
      $procedure $w
      foreach child [winfo children $w] {
        walker $child $procedure
      }
    }


    proc check_width w {
      switch [winfo class $w] {
        Button -
        Label {
          set original_width [$w cget -width]
          set x_extent [winfo reqwidth $w]
          $w configure -width 0
          set needed_x_extent [winfo reqwidth $w]
          set result [expr $needed_x_extent > $x_extent]
          $w configure -width $original_width
          return $result
        }
        default {
          return 0
        }
      }
    }
then execute
    proc c w {
      if [check_width $w] {
        puts "Widget '$w' isn't wide enough."
      }
    }

    walker . c

The truth is, that's not '''exactly''' what I do, but it's close enough.  For sufficiently
weathered applications, and especially ones that have moved around between
platforms, I usually pick up a few widgets that I'd rather find this way than by
having a customer complain.
----
[FW]: I didn't read this page completely thoroughly, but it appears to me that all you need is to use ''grid'', configure the column uniform, and make the buttons sticky ew.  Any special code to make the buttons match each other's width calculatively is very likely misguided and needless.