Hi, 

From: Ralf <lausianne / gmx.net>
Subject: How to make TkLabel update immediately?
Date: Fri, 17 Jan 2003 18:05:12 +0900
Message-ID: <3e27c499$1 / epflnews.epfl.ch>
> I'm putting out some text in a window using a TkLabel. The problem is 
> that the text only seems to appear once the method has finished.
> Is there a way to make labels update after .configure immediately?

Tk re-draws widgets on a idle-task. 
Because an operation of the 'command' option is one event-task, 
Tk never call an idle-task before 'exit' of your script.
You must call 'Tk.update' or 'Tk.update(true)'.
'Tk.update(true)' forces to run Tk's idle-task. 
For example, 

> Code example:
>    btnExit = TkButton.new() do
>      text "Exit"
>      command {
>        label.configure ("text" => 'Good bye!') #never appears!

         Tk.update    # <= You need this !!

>        sleep 2
>        exit
>      }
>    end

-- 
                                  Hidetoshi NAGAI (nagai / ai.kyutech.ac.jp)