[SOLVED] -/+ Tile X,Y (for Parallax-effect)

I want to create a simple first-degree parallax effect. This means having something larger and visible slide around in a viewport-like area. I only want the viewport section visible. I know this’d be as easy as allowing negative values for position. That doesn’t work for Tiles in a Tilemap. What will stay an absolute size while being allowed to move left of (0,0)?

When happens when you use it this way in Tilemap?

Me attempting to set negative x,y values for a tile in a tilemap simply doesn’t happen. Is that by design or should that actually be possible to do?

-Edit-
Correction, negative values do work. I am terribly sorry for the false alarm. I will be more careful before posting.