How to show Debug tabs side by side

Hi everyone, 

I read in the documentation the following: "If you are unhappy with the default layout of the Debug tool window, you can always move the tabs and areas. To do that, just drag a tab or an area to the desired location."

In order to compare the debug output of two different programs I would love to show it side by side instead of in different tabs. However, as much as I drag the tabs around they never show me a target area and on dropping it nothing happens.

What am I doing wrong?

Thanks in advance!