LyX math macros in action

The recent LyX versions have a feature called math macros for some time. It is more or less the graphical version of \newcommand from the LaTeX world. Though there is a small difference, namely that you can give a different definition for the LaTeX code and the screen code. This concept has some really really useful consequences: you can enhance your WYSIWYM editor LyX into a graphical proof builder, a graphical lambda term editor and so on.

This is half true though because the macro implementation in the released LyX is just totally stupid. If you click on a macro term it unfolds into a generic representiation with a list of arguments. This has the consequence that first of all you loose (again, like in LaTeX) the overview of your formula (no WYSIWYM anymore), and second under certain circumstances (e.g. in combination with \left( \right)) LyX formula display can grow, even exponentially in the nesting depth of macros. This makes it unusable.

But fortunately it was only a matter of a day to fix that and the result is a fantastic flexibly enhanceable LaTeX frontend: