For whatever reason, when the trailer and semi dock together, the camera will get stuck and inputs will break. I've had to restart entirely and resetup stuff because I could not use the quickload/quicksave buttons because they broke. Pressing on UI stuff doesn't really work either. I don't know why.
To reproduce:
Hit [ Until you get to the trailer, then slider 1 up to lower the trailer. You will probably have to mess around with it a bit until it eventually connects.
Once it connects the camera and inputs should but out. You should not be able to reposition the camera at all, nor use any UI items.
I would post a video of it.. but I'm being rather lazy today. Sorry.
This should be fixed in 0.6.8.