Closing a terminal window also closes any drop-down terminals that were open in the background
Scenario: I have a xfce4-terminal drop-down window open in the background, now I open a new terminal window, for example by using the "Open terminal here" context menu in Thunar. After finishing whatever I was doing I close the terminal window, this also closes the drop-down window in the background with all it's tabs and whatever might still have been running in there.
xfce4-terminal version 1.1.1 on openSUSE Tumbleweed