Split Window Command (Shortcut Menu)
You access this command by right-clicking
inside an open file in the Quartus® Prime Text Editor, and then
clicking Split Window.
Allows you to split a Quartus® Prime Text Editor window into two panes. Any changes you make in the active window will appear in the inactive window. By default the split window has a vertical orientation. You can change the orientation by clicking Text Editor in the Options dialog box.