Feature request: lock/protect window

[mmindenhall]

I have a Firefox window in which I always keep 5 tabs open:

• work mail
• work calendar
• personal mail
• personal calendar
• personal contacts

I lock and protect those tabs so they can't be closed or modified accidentally.

What I'd like to be able to do is lock the window itself so no other tabs can get created. I.e., when I click on a link in an email, it currently gets opened in a new tab in the window. With the window locked/protected, a new tab would be created in another existing window (e.g., last active), or a new window if there are no other windows currently open.