Processing.js

great library but:

//Can you simplify this ?
if (obj === null || other === null) {
      return (obj === null) && (other === null);

//.. do I need braces ? Throwing Strings ? Not good for onerror handlers... 
throw ("XMLHttpRequest failed, status code " + xhr.status);

// try to count number of "this." in minimized version ;-(
 
// how many times will you call the same functionn in one line....
a.charAt(0) === "(" || a.charAt(0) === "[") return a.charAt(0)

//loops; could be even shorter right ? (++ vs. --)
a = 0;
for (c = h.length; a < c; ++a) h[a].owner = this;

//could you be more verbose ?
//hardly !
DrawingShared.prototype.vertex = function() {
      var vert = [];

      if (firstVert) { firstVert = false; }

      if (arguments.length === 4) { //x, y, u, v
        vert[0] = arguments[0];
        vert[1] = arguments[1];
        vert[2] = 0;
        vert[3] = arguments[2];
        vert[4] = arguments[3];
      } else { // x, y, z, u, v
        vert[0] = arguments[0];
        vert[1] = arguments[1];
        vert[2] = arguments[2] || 0;
        vert[3] = arguments[3] || 0;
        vert[4] = arguments[4] || 0;
      }

      vert["isVert"] = true;

      return vert;
    };

etc..etc...

TODO: will be continued