[cairo] RCairo: warning: instance variable surface not initialized

[Stefan Salewski]

I have a Ruby/GTK/Cairo test application:

http://www.ssalewski.de/PetEd-Demo.html.en
http://www.ssalewski.de/peted.rb

Seems to work fine, but

$ ruby -w peted.rb

gives
 
peted.rb:207: warning: instance variable surface not initialized


205  def paint
206    cr0 = @darea.window.create_cairo_context
207    other = cr0.target
208    cr0.destroy

I am still new to Ruby and Cairo, so I have not really an idea what is
wrong.

I know, for GTK+ 2.22 there is a new
gdk_window_create_similar_surface ()
which will make life easier, but I still have only 2.20 (Gentoo), and
the application should really not require latest GTK.

Best regards,

Stefan Salewski