Quick Greasemonkey Hack to see if this was the only issue for Firefox in a "My God, it's Full of Sinus" (http://awsm.de/)

canvaswrap.js

// ==UserScript==
// @name        CanvasWrap
// @namespace   Greggman
// @description Wraps the Canvas
// @version     1
// @grant       none
// ==/UserScript==

CanvasRenderingContext2D.prototype.drawImage = (function(oldFn) {
  return function() {
    var args = Array.prototype.slice.call(arguments);
    if (args.length == 9) {
      var img = args[0];
      var sx = args[1];
      var sy = args[2];
      var sw = args[3];
      var sh = args[4];
      var dx = args[5];
      var dy = args[6];
      var dw = args[7];
      var dh = args[8];
      
      if (sw <= 0 || dw <= 0 || sh <= 0 || dh <= 0) {
        return;
      }
      
      dx = dx || 0;
      dy = dy || 0;
      
      var srcToDstWidthFactor  = dw / sw;
      var srcToDstHeightFactor = dh / sh;
      
      // clip left
      if (sx < 0) {
        sw += sx;
        dw += sx * srcToDstWidthFactor;
        dx -= sx * srcToDstWidthFactor;
        sx  = 0;
      }
      // clip right
      if (sx + sw > img.width) {
        var delta = sx + sw - img.width;
        sw -= delta;
        dw -= delta * srcToDstWidthFactor; 
      }
      // clip top
      if (sy < 0) {
        sh += sy;
        dw += sy * srcToDstHeightFactor;
        dy -= sy * srcToDstHeightFactor;
        sy  = 0;
      }
      // clip bottom
      if (sy + sh > img.height) {
        var delta = sy + sh - img.height;
        sh -= delta;
        dh -= delta * srcToDstWidthFactor;
      }
      
      // NOTE: It's not clear if I should adjust dw,dh or not. I have no idea
      // what is intended
      if (sw > 0 && sh > 0) {        
        oldFn.call(this, img, sx, sy, sw, sh, dx, dy, dw, dh);
      }
    } else {
      oldFn.apply(this, args);
    }
  };
}(CanvasRenderingContext2D.prototype.drawImage))