Nice, comfortable Puntuado con 4 de 5 estrellas

But I don't know how to save tab configuration. I spent a good piece of time to configure it, but after closing it only one tab in each pane left...

Esta valoración es de una versión anterior del complemento (0.3.3.1-signed.1-signed). 

Can not reproduce...

The tab configuration is automatically stored into Firefox's preferences. If you open about:config and search for "firecommander.state", does this value contain your tabs and their state/paths?

What FF version and OS do you use?