Most students did fairly well in getting the functionality
working and the marks reflect this. Few students got 100%
for the style and documentation, so here are a few things
that people did wrong:

(**) Putting too many variables in too global a scope.

(**) "Magic" numbers or strings scattered throughout
     the code (this is what final variables are for).

(**) Declaring variables with apparently the same use 
     as those in a superclass 
     (hint: Frame already has a height and a width).

(**) Not commenting variables.

(*) Using meaningless, short, class and variable names.

(*) Unused methods and variables.

(*) Classes that appear to have identical form and function
    to classes already in the Java libraries.

(*) Silently catching and ignoring exceptions.

(*) Not catching exceptions.

(*) Not giving any comments (in some cases not even the
    authors' names)

(*) Incorrectly packaged jar file
    (hint: the command "java -jar <file>" should run the code)

(*) Not generating the javadoc files.

(*) Using the wrong filename to save points.

(*) Not including all the necessary files 
   (the assignment clearly asks for .java, .class and javadoc files)

(*) Storing points in fixed-sized arrays that overflow.

(*) Commenting groups of variables:
         /** These are the coordinates */
             int x;
             int y;

(*) Meaningless comments, basically just paraphrasing the code, e.g.:
    /** A private int data-field holding the value of d */
    private int d;