I often have the problem that “old” windows are reopend after starting Nitro again although having been closed during the last session.
This results in taking a long amount of time on startup and then having e.g. 3 windows for the same folder.
Yes, it’s on my list to fix. Sorry about that. The problem is that it’s not very reproducible. It happens and then it stops happening as I’m trying to figure it out! You might try moving the windows (or resizing them) and then closing them. That might work around the problem.