Run the code.

Look at the movie.

If I set slider to a value less than 0, progress bar disappears, and you can see according to the output, that y becomes 0.

Sample output:

run:
BoundingBox [minX:0.0, minY:0.0, minZ:0.0, width:100.0, height:0.0, depth:0.0, maxX:100.0, maxY:0.0, maxZ:0.0]
BoundingBox [minX:0.0, minY:0.0, minZ:0.0, width:100.0, height:10.0, depth:0.0, maxX:100.0, maxY:10.0, maxZ:0.0]
BoundingBox [minX:0.0, minY:0.0, minZ:0.0, width:100.0, height:0.0, depth:0.0, maxX:100.0, maxY:0.0, maxZ:0.0]