It was in 9.5.5, actually. Here are the two client settings:
Requires Client Restart: YES
Description: Blocks the user from dismissing the “while action is running” message dialog. The system menu on Windows and Mac is disabled, blocking minimize and maximize as well. Only the close functionality is blocked on Unix/Linux. The user can still minimize or maximize the message box on those platforms.
Requires Client Restart: NO
Description: set to 1 to cause “while action running” message dialog (when configured to display) to stay topmost. Note: On Unix and Linux platforms, this functionality requires a window manager that supports the “Extended Window Manager Hints” specification.