There is nothing complicated about this Add-On. Click on the icon to open the UI, and click on Save All Current Tabs. That is it. All tabs are saved from all open windows. If you have two identical tabs opened, it will only save one. The saved tabs will remain even if you clean the browser's cache and cookies. This just the Add-On I was looking for.

This extension is exactly what I needed. It's simple and uncomplicated,but provides the very thing I was looking for. I have a bad habit of opening something in a new tab to look at later, and end up with Dozens of open tabs. I have ADHD, which means "out of sight, out of mind", so bookmarking stuff doesn't work for me. Thanks for making this!

Is not enough four options:
1. Slots to save. At least 5 pieces. Sometimes you need to save multiple sessions.
2. Opening the URL list from the buffer. This is a related task and it should be here.
3. Save the list of open tabs to the clipboard
4. Save the list of saved tab URLS to the clipboard. Or saving the slot list to the buffer, see point 1.

The slots buttons will fit perfectly above the URL list, horizontally. )