No, this is the line :
var canvas = $('<canvas width="'+ (numb($text.btOuterWidth(true)) +
opts.strokeWidth*2) +'" height="'+ (numb($text.outerHeight(true)) +
opts.strokeWidth*2) +'"></canvas>').appendTo($box).css({position:
'absolute', top: $text.btPosition().top, left: $text.btPosition
().left, zIndex: opts.boxzIndex}).get(0);
Which needs to be changed to something like :
var canvas = $(document.createElement('canvas')).
attr('width', numb($text.btOuterWidth(true)) + opts.strokeWidth*2).
attr('height', numb($text.outerHeight(true)) + opts.strokeWidth*2).
appendTo($box).css({position: 'absolute', top: $text.btPosition().top,
left: $text.btPosition().left, zIndex: opts.boxzIndex});
I didn't test it, so I'm not sure it will work, but in theory it
should !