Линии меняют x и y при нажатии мыши.

/*
* Компилиpовать: javac resizer.java
* Запускать: appletviewer resizer.htm
* JDK 1.1.5
*/
import java.applet.*;
import java.awt.*;

public class resizer extends Applet {
final int inc = 25;
int max = 400;
int min = 200;
Dimension d;
public void paint(Graphics g) {
d = size();
g.drawLine(0,0,d.width,d.height);
g.drawLine(0,d.width,d.height,0);
showStatus(d.width+"x"+d.height);
}
public boolean mouseUp(java.awt.Event evt, int x ,int y) {
int w = (d.width+inc)>max?min:(d.width+inc);
int h = (d.height+inc)>max?min:(d.height+inc);
resize(w,h);
return true;
}
}
/*
==== resizer.htm ====






==== resizer.htm ====
*/