iTerm2 - merge a pane back to window or tab bar

You can easily drag a pane or tab out as a separate window in iTerm2. Just left-click the header and drag it outside its original window. However, you cannot simply drag it back.

The secret key combination to drag a pane back to a window or to the tab bar is: command + shift + option, while dragging the pane body (not its header!). View the screencast below and you’ll figure it out:

You can find the screencast in full resolution here.

Many thanks to this post and this discussion.