A tabbed note editor instead of separate windows

Now each time a new note opens in a new window, and any note in principle - in a separate window. This is not very convenient and outdated. I hope that as part of the move to the QT framework, this will be fixed in version No4.

P.S. I see on the forum that the author has moved a little away from the development and I understand it, a difficult time, the situation is very dramatic, but...

(And you have no idea how convenient your program is still for working with information! No matter how much I tried, I could not and did not want to master the same "Obsidian", well, this is not my thing.)