Its last version was 1.01 and it was based on the last version of MTgui, which was an interface only for ModelTest. MrMTgui was developed in C++/wxWidgets and it was freely distributed and open-source.
Currently not available.
To get the source, drop me a note at nuin at genedrift dot org
MrMtgui was replaced ModelPie which is available for all systems.