The scrollbar thumb is the wrong size. If a minimum and maximum are specified, the value set to minimum, and the current page size set to maximum - minimum (ie show the whole page), the scrollbar thumb is displayed as half a page.

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package test;

import java.awt.*;


// simple frame to view a scrollbar with tumb incorrect size
class ScrollThumb extends Frame {

    ScrollThumb() {
        setTitle("ScrollThumb");

        Scrollbar vscroll = new Scrollbar(Scrollbar.VERTICAL);
vscroll.setValues(0, 300, 0, 300);

        setLayout(new BorderLayout());
        add("Center", new Bogus());
        add("East", vscroll);
        pack();
    }

    
    public static void main(String[] args) {
        ScrollThumb frame = new ScrollThumb();
        frame.show();
    }

}

class Bogus extends Canvas {

    public Dimension getPreferredSize() {
return new Dimension(300,300);
    }

}