Want shortcut to start Task Manager and kill to Firefox - in one step

I want to have a shortcut on the taskbar that will start Task Manager use it to kill Firefox - in one step. This will preserve the open tabs on multiple windows for the next startup.

Jacee said:

Have you tried this? https://support.mozilla.org/en-US/kb...evious-session

That worked. I had been closing down with the X. That only saved if the window was the only window open. Previous windows closed with X were lost. But when I shut down all FF windows at once with [file] [exit] I got the option to save. Thanks.