plPointSize(float) is not working in Qt 4.7.

I want to draw some different size points using opengl. However, glPointSize(float) is not working. I can draw a few simple shapes on the screen. However, this command just does not work. All I see is a few tiny dots. I have posted sample code.

void GLWidget::paintGL() {
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1,0,0);
glBegin(GL_POINTS);
glPointSize(10.3);
glVertex2f(0,0);
glVertex2f(.2, .5);
glVertex2f(-.4, .3);
glEnd();
}

Can someone help with this?

Does it work in a non-Qt application?

Yes, I tried this in command line and it works just fine.

What do you mean by "in command line"?

This means without graphical user interface. This can be done by Qt console application.

So it does work with Qt but not when you display the GL result in a window? I was rather asking you to write a simple GL code without Qt and see if glPointSize() works there. It simply might be a matter of DPI or something similar.