Problem: I need to compare two worksheets from the same workbook side by side.
Strategy: This is possible! Chose View, New Window.
You will notice that there is now a :2 in the title bar after your file name. You've just created a second "camera" that can focus on a different area of your workbook. The second view can either be another worksheet or a different area of the current worksheet.
Do Window, Arrange, Vertical as described in the previous topic. You will now see the :1 version and the :2 version side by side. Navigate to another worksheet in the :2 version.
To remove the :2, switch to the :2 version of the workbook and click the Close Window (X) icon to close that window.
You might worry that this will close the workbook without saving. Instead, it will close the second window of the workbook and both the :2 and :1 will be removed from the title bar. The workbook will remain open.