#include <QOpenGLWidget>
#include <QOpenGLFunctions_3_0>

class TestGraphicsPane : public QOpenGLWidget, public QOpenGLFunctions_3_0 {

  Q_OBJECT

public:

  TestGraphicsPane(QWidget *parent=NULL) : QOpenGLWidget(parent) {
  }

  void initializeGL() {
    initializeOpenGLFunctions();
  }

};

TestGraphicsPane *graphics;

void MainWindow::on_Button1_clicked() {
  graphics = new TestGraphicsPane();
  TopFrame->layout()->addWidget(graphics);
}

void MainWindow::on_Button2_clicked() {  //Invoking this function causes crash.
  graphics->setParent(0);
  delete graphics;
}