Brilliant!

Will there be a toolbar icon in a future release?

Can't do without it.

Simple, fast, provides exactly the functionality needed, and so easy: just right-click to get the tab context menu and click on the Merge all windows option. Thank you!

No right click button button or anything to merge windows.

Please give usage instructions in the description.
e.g. Merge Windows is in the right click menu

MW works.

Excellent!
It simply works!
And is fast! :-D

Really not too much intuitive for first-time use.
A more clear one-line instruction about the 'right-click' way would be useful.

Absolutely amazing idea, I love it!

Simple and work as aspect.

Simple and easy to use. Merge to focused window.

Very useful addon, thank you! Have you considered making a version or implementing a setting that would always merge all windows automatically should they be opened? That the only thing this addon's missing to be perfect.

Nice addon. Does what it says

super useful feature

Simple and easy to use.

The Chrome version of this add-on is more elegant, but this certainly works and is so invaluable I find it hard to believe that neither browser has made it a default capability.

It'd be great if the documentation could make it more explicit that the Merge Windows command gets added to a right-click menu and not the main browser menu. Right-clicking on a specific webpage to find an option that affects all Firefox windows is plenty functional but not intuitive.