Unsolved to show a qwt3d object at somewhere specified

[Make it GREAT again]

Hello,
I want to use GridPlot to show points given by serial port data. I tried duplicating a demo and re-configure its project as a single project. That works well but don't know how I can show it in another UI.
For example, the object is declared as a member of TestGUI inheritted from QMainWindow
#include <QMainWindow>
#include "difplot.h" // given simply qwt3d plot things

namespace Ui {
class TestGui;
}

class TestGui : public QMainWindow
{
Q_OBJECT

public:
explicit TestGui(QWidget *parent = 0);
~TestGui();

private:
Ui::TestGui *ui;

Qwt3D::GridPlot * oPlot;

};
#endif // TESTGUI_H

What I can do to show it in TestGui.cpp if the main.cpp given as
#include "testgui.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
TestGui w;
w.show();

return a.exec();

}

[SGaist]

Hi,

Does TestGui contain a layout ? If so just add your plot widget to that layout.