This does exactly what it says - opens existing tabs as arranged and synchronized browser windows- and does it perfectly.

You can easily turn off the toolbar across all windows, syncronize scrolling between them, and realign them if you disturb the original configuration. You can set a default layout, and pick a different one at any time. The menus are clear and intuitive. It will close the splits as easily as it opened it, restoring them all to tabs.

I love this add-in! Thank you developers!