I found a problem in the previous patch, new one added. This patch now
only considers tuple and list as possible option value that should be
joined, and the items inside the list or tuple should be either a string
or integer, otherwise it doesn't try to join the values.

The problem in the previous patch is that it would always join the value
independent of the value's content. But if an option is composed of a
tuple of tuples (used by dialogs), this conversion shouldn't be done.