Sorry Will, Messy is not what we want. I've done a demo in TW Math.

I am very happy with the simple TiddlyWiki markup we already have. The re-editing of formulas is a nice luxury and should be easier than that if I can make myself clear.

There is no need to launch the TW version of the editor or to return the formula to a textbox. Opening the editor with the desired code already inserted is all that need be done, identical to Numbers Empire. After reediting the user just copies the changed formula from the editor's edit box and pastes it back into TW where they wanted it changed. (They could click the add to clipboard button but I've never seen it work in any version of Equation Editor I've seen)

Please follow this link where there are working models of what I had in mind. You can see the code and click on the links and see it work as I described.

http://twmath.tiddlyspot.com/#ReEditFormula

Morris