[Fix] Browse into UDF image files.

@jmarshallnz I think it has to do with the curl changes, but not sure. I guess ```strSub``` should be the relative path, i.e., everything after ```*.extension```, at least a test with ```""``` and with ```"/"``` worked.

This does not fix the problem, but only a part of it. (Sorry that I misuse it as a bug ticket)