canvas.on() does not work

[ppr-lu]

This does not work: var c = new fabric.CanvasWithViewport("zoomable_canvas"); c.on({ 'mouse:down' : function(){console.log("canvas mod.");}, 'mouse:up' : function(){console.log("canvas mod.");} });

But if i change c to: var c = new fabric.Canvas("zoomable_canvas"); it does.

EDIT: Only happens when c.isGrabMode === true. When it is false event handlers work properly.