Simple custom Swing JComponent always flat

Question

I'm just playing with Swing and I'm working on a really simple Swing component. I have a component inherited from JComponent class and its UI inherited from ComponentUI. The paint() method looks like this:

public void paint(Graphics g, JComponent c) {
    int x = c.getX();
    int y = c.getY();
    c.setBounds(x, y, 100, 25);
    int width = c.getWidth();
    int height = c.getHeight();
    Rectangle r = g.getClipBounds();
    g.fillRect(0, 0, 10, 10);
    g.drawString("Baf!", 3, 3);
}

But it is totally impossible to get another value of r.height than 1. The component is width as given, but height allways one point only. Has anybody else experiences with suchlike components? Unfortunately there is no any easy tutorial. All tutorials are incomprehensible complicated (or obsolete).

It seems, that the layout manager resizes this component allways to 1 height (regardless to minimal value).