In 'OpenFilesCallback':
* if a directory file is selected then all of the files in the
directory(s) will become
candidates for selection after being 'filtered' for passing to the
'openFiles' method;
* if 'singleFile' attribute is true as set in 'OpenFileOptions'
class the the first
'filtered' file in the directory is passed;
In 'File':
* needs a 'URL' string attribute;
These additions would, e.g., allow for the selection of all .jpg's in
a directory hierarchy.
I will gladly develop the 'patch' code if thought useful by the team.
