Here I open a layout; as you can see it seems to be greater than the variant. Changing some of its properties (i tried only Show Title and Full Screen), it "is resized" well.
From tests done, at least in my case is well displayed by centering the panel using a script.
Creating the test project I discovered that the bug happens only when you open a layout ("layMain", here) from menu; opening it from the Files Manager it's ok.
I forgot to write that, again creating the test project, the error did not occur when only one layout was created (layMain).
This is why I created the second one (and the second Activity, but this should not affect).