FabicJS UI block on canvas update

FabicJS UI block on canvas update

i am using twitter bootstrap and fabricjs. so one page I have canvas and i
fire off a method that updates the canvas (add some objects to it). while
that is in progress i show a modal popup with a animated gif.
the problem is that once the canvas update operation starts the gif
animation stops, i am assuming this is due to the UI thread being blocked.
is there any way the canvas updating can be done on a separate thread.