I think it would give Sencha Animator projects bigger flexibility, if it would be possible to change resolution/animation size at any time. Clients like to change things often Many times I had to change resolution of banner or even swap height and width proportions. Now, you would have to recreate a lot of stuff in Sencha Animator. Being able to change size without recreating whole complex animation, would be a huge time saver for me.
Another nice thing would be way to scale whole animation to fill newly defined animation area.
I.e. lets say I got 200x500 pix animation. I want to change it's size to 250x600. So I type in new size, and mark "scale to fit area". Then animation area increases and all elements of animation are scaled proportionally to fit newly defined area, so you don't have to take care of white margins (of course if proportions of newly defined area are bit different than original, you got to do some manual adjusting anyway).