I'm running the linux build of processing on Ubuntu. I'm building some sketches with Eclipse, but when I go to run them as a java application, they instantly crash/freeze with no error when I put my mouse over the window. I've tried very simple examples such as the following, but it  just stops as soon as the mouse is in the window. Anyone have any ideas?
Code:

import processing.core.*;

public class Test extends PApplet {

    public static void main(String args[]) {
        PApplet.main(new String[] { "Test" });
  }
	
    float a = 100;

    public void setup() {
        size(200, 200);
        stroke(255);
        frameRate(30);
    }

    public void draw() {
        background(51);
        a = a - 1;
        if (a <0) {
            a = height;
        }
        line(0, a, width, a);
    }
}