The daum equation editor is an excellent online gui to latex editor for turning maths into latex.
The original site is here: http://s1.daumcdn.net/editor/fp/service_nc/pencil/Pencil_chromestore.html
The source was made available here:
I used this portable version of basilisk https://archive.org/details/basilisk-portable-with-flash
with a custom css to produce a version of the equation editor that looks like a native app and works entirely offline:
I set it up to launch with the portableapps launcher with it's own icon, and standard-ish portable apps folder layout.
The launcher is a .bat.
It does what I need to do and well.
Please note I am not interested in learning in depth how to make fully, properly, spec compliant portableapps. I just want to share what I've done. Is it possible? How?