Rick A. said: How do you mean "mark"? Are you asking for the VTT to automatically adjust how it measures token movement? Yeah, so when you measure over an area it shows that its difficult terrain with a symbol, and correctly adjusts the lenght, or perhaps shows a symbol for ease of movement, and halfs the cost over it. Perhaps it could be used for other things as well, showing if line of sight works or not, things like that! :)