How do I get a code window to split vertically in Visual Studio 2008? (not HTML mode)

Ok, I found the solution here.

The answer is:

1. Window -> New Window
2. Window -> New Vertical Tab Group

This duplicates the current tab so you’ll get [Form1.cs:1] and [Form1.cs:2] tabs; and then you can use a vertical tab group to view them side by side.