Visual Studio: How do you dock two Debug Windows Side-by-Side? (Immediate & Call Stack)

Question

QUESTION how do you DOCK two DEBUG windows side-by-side?

For the last year while debugging I had the Immediate Window DOCKED NEXT to the Call Stack window, both visible at the same time (as depicted by the attached image). Then last week I lost this desired config by fat fingering an unknown sequence.

After hours of Googling and experimenting I can't for the life of me reproduce this config. Best I can do is float them (depicted in image). Window > Reset Window Layout didn't help. Window > New Horizontal Tab Group seems to apply to code windows only.

Answer 1

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Further reading: How to: Arrange and Dock Windows on MSDN