I am having same issue. The mouse while playing the game will not go all the way to the right. In game menu, when it switches to the traditional looking mouse cursor it can go all the way to the edge as normal.
Having a problem with the train because of it. It's on the panel in the engine cabin, on the panel labeled 6. I can't reach the last switch on the right of the panel and it needs to be flipped. As OP stated, the mouse cursor barely will read the second to last switch.