Firefox has a tab bar context menu item "Move to New Window". This will create a new window with all the default window configuration, incl. vertical tabs, location bar and whatever else one might have.
I occasionally want to move a web application from regular tab into an "app"-like window, i.e. all the window.open features removed. Also known as a popup.
Sounds like an addon, but I'm not finding any so far.
Any other tricks or suggestions in the meanwhile?