Two frames open with screen split horzontally -- how to do

Good morning,
I suspect I’m missing something elementary.

For example I’d like to have the calendar open at the top and the flow board beneath it. If I lock one , the next one I open splits screen vertically.

How can I open multiple items with screen split horizontally.

Thanks
Bob
openemr 7.0.2
google chrome

Vertical split example – not what I want