Suppose you have a terminal with two tabs. You click, drag, and let go one of these tabs and it becomes an independent terminal window. After a while, you want to take this terminal window and reattach it as a tab to the previous window. How do you do it ? I have seen the merge windows option in the menus, but that merges all windows into one, which I would then have to revert.
You need to, in the window you want to move, go to View-> Show Tab Bar (if the tab bar isn't showing already).
Then, drag the tab of the window you want to move onto the window you want to move it to.
Update for iTerm 2: In iTerm 2 the setting is no longer exposed in the View menu. Go to iTerm > Preferences > Appearance and check "Show tab bar even when there is only one tab". Note that in early releases of iTerm 2 the setting was "Hide tab bar when there is only one tab".
The answer is to hold down command + shift + option whilst dragging the body of the terminal (not the tab) back to the terminal you wish to merge.
I had troubles merging windows with the Hotkey Window profile. I eventually found a way to un-split the windows by doing the following:
Hide tab bar when there is only one tab
- Press your hotkey to show the Hotkey Window
- Click & drag the tab into the Hotkey Window's tab bar