Could there be a selection box / button just below the editing box, and before the Markdown Preview to enable / disable the MathJax.
When I was editing a question, I was finding it quite distracting that ever time I typed something, the box jumped about because of the height of the MathJax. It had o refresh every time, and this was quite irritating.
I would like to be able to enable / disable the MathJax sections before I have finished editing - perhaps with a toggling button or a check box.