Rated 3 out of 5 stars

sashabe কর্তৃক আগ. 19, 2016 তারিখে ·

It works, but the tabs in all the windows but first one get reloaded upon merging, thus losing any text input or saved data in there.
Also, a nicer place for Merge windows command would be in Window menu.
At last, a nice to have functionality would be to add Duplicate to Private Window — this is often useful for debugging websites.