korm
macOS 10.11.5

Open v9.   Select a tab.  Open Preferences (or ⌘,).  Minimize Preferences by pressing the middle (yellowish) stoplight button.  The Preferences are minimized, but also the main window. 

Usually Preference windows are not minimizable -- because Preferences is modal.
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pthompson
korm,

Thanks for the report. I'll make sure it's documented.
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