How do I replace a widget?

[pir]

Hi!

I have a GLWidget that shows a 3d scene. When I open a file with a scene in, I need to replace that GLwidget with a new GLwidget with the loaded scene. The problem is that the program spits out a lot of exceptions when I close the program. So I suppose that the widget holding the GLWidget still tries to destroy the old GLWidget when I close the program. I'll spare you the long list of messages, but it starts with ***glibc detected*** double free or corruption.
Is there any way to solve this?

This is my attempt to do this:

/*
         canvas is the GLWidget holding the 3d scene.
    */
   mainLayout->removeWidget ( canvas );
   canvas->hide ( );
   canvas->setParent ( NULL )
   delete canvas;
 
  /*
      Creates the new GLCanvas containing the new loaded scene....
 
   */
   canvas = new GLCanvas ( newScene, this );
   mainLayout->addWidget ( canvas );

/*
         canvas is the GLWidget holding the 3d scene.
    */
   mainLayout->removeWidget ( canvas );
   canvas->hide ( );
   canvas->setParent ( NULL )
   delete canvas;

  /*
      Creates the new GLCanvas containing the new loaded scene....

   */
   canvas = new GLCanvas ( newScene, this );
   mainLayout->addWidget ( canvas );

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hope I've explained the problem in a understandable way...
thanks for reading
pir