Edit formula on click

[cben]

No description provided.

[cben]

A quick attempt to unrender a formula on click failed because of event order:
if you do it while already inside another formula, the click handler wants to unrender the 2nd formula before the 1st is rendered back, which breaks the current code assuming at most one formula can be unrendered at once.
Should change unrenderedMath variable to a list.