Test code to reproduce the bug

test.rb (text/plain), 512 bytes, created by Andreas Schäfer on 2005-11-06 10:05:52 UTC

#!/usr/bin/env ruby -w

require 'Qt'

class MyWidget < Qt::MainWindow
  def initialize()
    super
    @canvas = Qt::Canvas.new(640, 480)     
    rect = Qt::CanvasRectangle.new(10, 10, 50, 50, @canvas)
    rect.setBrush(Qt::Brush.new(Qt::green))
    rect.setPen(Qt::Pen.new(Qt::red))
    rect.show

    @canvas_view = Qt::CanvasView.new(@canvas, self)
    self.setCentralWidget(@canvas_view)
    @canvas.update
  end
end

a = Qt::Application.new(ARGV)

w = MyWidget.new
w.show

a.setMainWidget(w)
a.exec()
exit