Theoretical key support
It would be a nice addition if theoretical keys (with 8 or more (i.e. involving double) sharps/flats, e.g. G-sharp major or F-flat major) were supported in MuseScore. It can help both with adjusting the parts for transposed instruments (showing in an enharmonical keys), or just for score writing (e.g. one of my composition begins in A-flat major and ends in G-sharp major, with meaning "things are returned to their places but the situation has significantly changed", so I cannot just use A-flat since it would ruin the whole main idea. Currently, I've sticked to using C-sharp major and explicitly writing all double sharps).
Although I'm a C++ developer, I'm not sure that I can contribute to this (and that community will accept it).
Thank you in advance and sorry for my bad English.