userDir should finish with the /, the userFile should just be the filename.

I would harmonize to clef everywhere even if both seems valid.

we should hamonize the end of sentence, always use a dot seems better.

if I'm not wrong, you'll append everytime you click on save meaning that you'll have twice the same music if you save it twice?
It would be better to let the child choose the name of the music, and if a music already have this title, prompt the child to overwrite it if he wants.

Needs to be checked for later, if an export to wav would be possible/interesting to have.

copy/paste?

for now yes, its saved twice. Regarding the save yes I want to give it a name of child's choice :)
But then do we add a input text box to showMessageDialolg or should I create a new component with a button to save the file and pop another dialog if it exists to ask if it is to be overwrited?

But in this the child might get confused due to 1-2 windows :(

What do you think?

yes, just used the append option instead (the write overwrites the file)