Dear Mantainer I can confirm this bug in the keepnote package for Debian Stretch 9.1 (keepnote 0.7.8-1.1). I've found that the same bug appears too if using the source package from http://keepnote.org. (maybe the cause is some change in python?).
As the original report mentions, only folders on the left side of the dialog box can be opened, and those folders contents is always greyed out. No error appears on the graphical interface nor in the shell session where I started keepnote. Attempting to open a notebook passing it as a cli argument to keepnote produces the error: "Could not load notebook notebook-name" I can create new folders from the dialog box, create new notebooks, add content to them and save them. But if I close them and try to open again, the folder appears greyed out and cannot be selected. I have not been able to find a workaround that allows me opening previous notebooks.
