Found an easy way to know how many files you have and how much is their size!
1) export all links in tour account in TXT format (there are controls for this in the right column of the file manager)
2) open the downloaded file (Wupload-links.txt), select all rows and put them on JDownloader's linkgrabber
3) when JD finishes online checking, you should have a bunch of rows: select all, right click and select "Merge to one package"
The trick is done! Now you have a files count inside [] after the package name and a total size!!!
^_^
AtZ