Thank you for that info, I tried it and it works - I have set it to: language=en
Now I'm just trying to figure out if/how I can use that neutral file and I'm testing now what I have to set and what I can leave out.
That way I hope to have a client in which only the username & password has to be entered and the server address remains greyed out with the right info of course.
EDIT (added info): after installing and opening spark without logging in, the spark.properties is created.
I closed spark and copied the file from a working system with the correct settings but changed the username and removed the line 'password<xxxx>'" completely.
When I start spark again I get 2 problems:
1) there is an error stating the username or password is invalid
2) the server address becomes editable but the address is correct
Any idea if it's possible to avoid that username/password issue?
How come the server address becomes editable and can I change that afterwards back to greyed out?
EDIT 2: by deleting the %appdata%\spark\spark.properties file, I'm back to the original situation.
By leaving 'password=' the result is same as deleting the line completely as stated in my first edit.