DJVU not recognized

[cskcsk]

I have installed plugin Xdjvu.dll but XnView doesn't open djvu files. "Format of the file <...> could not be dtermined" message is displayed on attempting. The option to display all formats is set.
ALSO: I search image tool application to edit image data directly inside djvu files without disassemblig they to page's image format. F.e. Irfan Viewer can read and edit DJVUs but not save screen copy back to djvu file. XnView also declares ability to read DJVUs without saving back. Does it principal limitation of libs used or djvu format specific feature?
Thanks.

[helmut]

New DJVU format is not supported by XnView, see topic Cannot read a DejaVu file.