Can we change previews background to other colors?
like for example checkerboard so when user scale the preview window he can distinguish between output screen and preview screen.
I think it will be easier for users if there borderd frame that take defult project frame size inside preview window that scaled when preview window scaled
You can insert a Video Peeker before the output:
In general peeker modules produce the same output you get when you use Ctrl + mouse hover on a pin/wire.
Video Peeker specifically displays a checker background and also a border, so basically you'll get exactly what you asked for.