From: Joel VanderWerf <vjoel@...>
Date: 2005-07-08T06:23:59+09:00
Subject: Re: cross-thread violation in TkCanvas when clicked

David Brady wrote:
> Hi All,
> 
> The Pickaxe (2e) gives an example of drawing on a TkCanvas.  The code is
> published on the book's website here:
> 
> http://www.pragmaticprogrammer.com/titles/ruby/code/smp262.html
> 
> I run this with no changes.  When I click on the canvas, the script
> crashes with this message:
> 
> /usr/local/lib/ruby/1.8/tk.rb:1383: [BUG] cross-thread violation on
> ip_ruby_cmd()
> ruby 1.8.2 (2004-12-25) [i686-linux]
> 
> The offending line is simply the mainloop method:
>  def mainloop(check_root = true)
>    TclTkLib.mainloop(check_root)
>  end
> 
> I find nothing in the errata for the book about this script not working,
> so I assume the problem is with my ruby installation or my linux setup. 
> Any ideas where I can begin looking?
> 
> I am running Ruby 1.8.2 with KDE 3.4 on Kubuntu 5.0.4.

Works find for me, also with ruby 1.8.2, KDE3.4, Kubuntu 5.0.4. However,
 I built Tcl/Tk from scratch with pthread disabled (the default). This
was instead of using the ubuntu packages which seem to have pthread
enabled. See:

http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/147279