Force android to use full screen input box

[MidnightRover]

I typically use most apps in portrait, but when it comes to typing something into an input box, I turn it to landscape to use the bigger keyboard. However several apps want to keep a header at the top of the screen. So between this header and the keyboard itself, there are times when I have only a sliver of view of the input box that sometimes isn't even a line high. Facebook messenger is a good example of this, see the screen shot in the link below.

Can't see what I'm writing:
https://drive.google.com/open?id=15F_gOyx5rb62d3-axDvW1g-i7wO2i21J

What I want instead:
https://drive.google.com/open?id=1DPWgbowysA1aRFBUm4X0skEGtTXdL4b3

Is there anything that can be done about this? Is there an app or a setting somewhere that will force it so that I have the full screen input box?

Thanks for any help that any one can give.