While we are browsing in Google chrome,a lot of links create new windows instead of new tabs, so JoinTabs moves every tabs of each windows next to that tab where you click the icon of JoinTabs.You can also use the shortcut CTRL + m to merge windows. After installing the JoinTabs,reload all tabs to use the shortcut.It works also with popup windows,as Developer Tools. This is really an useful extension.
Click the following link to Install the new chrome extension:
https://chrome.google.com/extensions/detail/binjiceocgbfooocmheaenmmcominbpe