Request: even on split window mode, changing orientation changes the window size

Steps:
1. Have 2 windows on Windows OS, side by side, using the split window mode:
https://www.digitaltrends.com/computing/how-to-split-your-screen-in-windows-10/
One of Chrome (for example), and one of this tool.

2. On the device, change its orientation.

There is an issue with this:
The window of the tool exits split mode, and if it was portrait, its window is even partially outside of the screen.

See video:
[ice_video_20180329-142158.zip](https://github.com/Genymobile/scrcpy/files/1859844/ice_video_20180329-142158.zip)

What I'd like, is the ability to stay on same window size, especially on this case.

No source file, test, or entry point is named. Reproduce the issue on Windows with the tool and another window in split mode, then rotate the Android device; done means the tool remains in the same split-window size and stays within the screen after orientation changes.

Written by the indexing model from the issue text.