From: mhm26@... (matt)
Date: 2004-05-17T22:38:52+09:00
Subject: [Ruby/TK] Widget Internal Layout

Given the following code:

-------------------------------------
require 'ext/tkscrollinglistbox'

root  = TkRoot.new
text  = TkEntry.new(root, 'width'=>100)
list  = TkScrollingListbox.new(root, 'width'=>50, 'label'=>'Meow')

list.instance_eval { @frame.configure('background'=>'blue') }
root.configure('background'=>'yellow')

text.pack('side'=>'top', 'fill'=>'x',    'expand'=>true)
list.pack('side'=>'top', 'fill'=>'both', 'expand'=>true)

Tk.mainloop
-------------------------------------


and ext/tkscrollinglistbox being (method_configure basically calls a
method with a given value when used in TkComposite.configure - the
version in CVS has something like this, I just haven't updated....)


-------------------------------------
require 'tk'

class TkScrollingListbox < TkWindow
  include TkComposite

  def initialize_composite(keys={})
    keys = _symbolkey2str(keys)

    @label   = TkLabel.new(@frame)
    @list    = TkListbox.new(@frame)
    @x       = TkScrollbar.new(@frame)
    @y       = TkScrollbar.new(@frame)

    delegate('DEFAULT', @list)
    @path    = @list.path

    method_configure(:scrollbars, :label, :labelspot)

    @list.yscrollbar(@y)
    @list.xscrollbar(@x)

    @list.grid('row'=>1, 'column'=>0, 'sticky'=>'nsew')

    listbox_event = Proc.new {|e| $stderr.puts "HERE!";
self.event_generate(e)}
    @list.bind('<ListboxSelect>') { listbox_event['<ListboxSelect>'] }
    self.bind('<ListboxSelect>') {}

    @lblWhere  = 'top'
    @lblPlaced = false

    configure keys unless keys.empty?
  end

  def scrollbars(scroll)
     case scroll.to_s.downcase
       when 'both' then @x.grid('row'=>2, 'column'=>0, 'sticky'=>'ew')
                        @y.grid('row'=>1, 'column'=>1, 'sticky'=>'ns')
       when 'x'    then @x.grid('row'=>2, 'column'=>0, 'sticky'=>'ew')
                        @y.ungrid
       when 'y'    then @y.grid('row'=>1, 'column'=>1, 'sticky'=>'ns')
                        @x.ungrid
       when 'none' then @x.ungrid
                        @y.ungrid
     end
  end

  def label(text)
    if text.nil? then
      @lblPlaced = false
      @label.ungrid
    else
      @label.text text
      @lblPlaced = true
      @label.grid('row'=>(@lblWhere == 'top' ? 0 : 3), 'column'=>0,
'columnspan'=>2)
    end
  end

  def labelspot(value)
    unless value.nil? then
      @lblWhere = value
      label(@label.text) if @lblPlaced
    end
    @lblWhere
  end

  def method_missing(sym, *args)
    if @list.respond_to?(sym) then
      @list.send(sym, *args)
    else
      super(sym, *args)
    end
  end

  alias old_respond_to respond_to?
  def respond_to?(sym)
    return true if old_respond_to(sym)
    return true if @list.respond_to?(sym)
    return false
  end

end
-------------------------------------



My question is why doesn't the listbox in the TkScrollingListbox
expand and fill the frame when the frame gets more space -- I made it
sticky(news)... do I have a misunderstanding of the grid layout
manager?  Is the world completely topsy turvy?  Please help!  Thanks
:-)