How do I have a window span multiple monitors on macOS?

1. Please open 'System Preferences' and select the 'Mission Control' preference pane, where you will see an option labeled 'Displays have separate Spaces'

2. When this checkbox is selected, OS X will snap a window to whichever display that window has the most area on

3. When unchecked, OS X will allow a single window to span across multiple displays (including Duet) and will act as one large continuous display

- Any changes to this setting does require a logout -

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