From: Hidetoshi NAGAI <nagai@...>
Date: 2005-06-29T00:52:32+09:00
Subject: Re: Problem in binding IWidget combobox to event

From: "Markus Liebelt" <markus.liebelt@online.de>
Subject: Problem in binding IWidget combobox to event
Date: Tue, 28 Jun 2005 23:05:40 +0900
Message-ID: <op.ss21fixc444ivd@localhost>
> I managed lately to include an iwidget combobox in a UI I have written. If  
> normally used (by poking around with the mouse) everything works fine.  
> What I cannot manage if the user is using the keyboard.
    (snip)
> If you open that application, and drop down with the mouse and select with  
> the mouse, you see on $stdout your selection. If you open in any way, but  
> select then by using TAB (focus goes to drop down list) and ENTER, your  
> selection goes into the combo box, but is not reflected in the $stdout.

It seems a specification limit of an iwidget combobox.

> What do I have to get a binding for the different possibilities to use the  
> combo box? Or is there even an easier way, eg. by using a binding to the  
> variable that lays behind the combo box?

TkVariable#trace will be able to help you. Possibly, that is more
simple than getting the listbox component and binding to it.
For example, 
-----------------------------------------------------------
class Ex_Combo
   def build_form(root)
     frame = self.create_frame(:form, root)
     var = TkVariable.new
     cb1 = Tk::Iwidgets::Combobox.new(frame, #:labeltext=>'Example:',
            #:selectioncommand=>proc{puts cb1.get_curselection; $stdout.flush},
            :textvariable=>var,
            :editable=>false)
     var.trace('w'){
       # This is called twice when selecting an item. 
       # One is when clearing the entry and the another is when setting 
       # a new value to it. 
       # The following check is the one to ignore clearing step.
       unless (val = var.value).empty?
         puts val
         $stdout.flush
       end
     }
     cb1.insert_list('end', *['First entry','Second entry','Third entry'])
     cb1.grid('row'=>0, 'column'=>0, 'sticky'=>'news')
     frame.pack('side'=>'left', 'expand'=>'yes')
   end
end
-----------------------------------------------------------
-- 
Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp)