Dropping a file into the file field does not shorten the path

[koppor]

Setting: General file directory (of the database): C:\Users\Oliver\BTSync\lit

Result after dropping a file: file = {:C\:\\Users\\koppor\\BTSync\\lit\\IoT\\MA_Guth_JA.pdf:PDF},
Expected: file = {:IoT\\MA_Guth_JA.pdf:PDF},, because C\:\\Users\\koppor\\BTSync is the prefix of the filename.

I think, this worked in JabRef 2.11... Think, FileUtils is the class to look at. See also https://github.com/JabRef/jabref/wiki/Code-Howtos#get-absolute-filename-or-path

[Siedlerchr]

Should work with the changes I introduced in JabRef#2415