Hold Ctrl + right click?

[JonMyrlennBailey]

What is this all about? How do I stop it? It only seems to happen in Chase mode. Even with mouse hiding off right side of screen.

 

[pware]

Looking at your screenshot, and confirming it with my own experiment, an item of rolling stock (the diesel loco) is overlapping the mouse pointer which is on the right of the screen. My solution to this has always been to "hide" the mouse pointer at the very top right hand corner of the screen.